Piperidinone carboxamide spirohydantoin CGRP receptor antagonists

ABSTRACT

The present invention is directed to piperidinone carboxamide spirohydantoin derivatives which are antagonists of CGRP receptors and useful in the treatment or prevention of diseases in which the CGRP is involved, such as migraine. The invention is also directed to pharmaceutical compositions comprising these compounds and the use of these compounds and compositions in the prevention or treatment of such diseases in which CGRP is involved.

BACKGROUND OF THE INVENTION

CGRP (Calcitonin Gene-Related. Peptide) is a naturally occurring37-amino acid peptide that is generated by tissue-specific alternateprocessing of calcitonin messenger RNA and is widely distributed in thecentral and peripheral nervous system. CGRP is localized predominantlyin sensory afferent and central neurons and mediates several biologicalactions, including vasodilation. CGRP is expressed in alpha- andbeta-forms that vary by one and three amino acids in the rat and human,respectively. CGRP-alpha and CGRP-beta display similar biologicalproperties. When released from the cell, CGRP initiates its biologicalresponses by binding to the CGRP receptor which is a heterodimerconsisting of the G-protein coupled calcitonin-like receptor (CLR) inassociation with the single transmembrane protein known as receptoractivity modifying protein 1 (RAMP₁). CGRP receptors are predominantlycoupled to the activation of adenylyl cyclase and have been identifiedand pharmacologically evaluated in several tissues and cells, includingthose of brain, cardiovascular, endothelial, and smooth muscle origin.

CGRP is a potent neuromodulator that has been implicated in thepathology of cerebrovascular disorders such as migraine and clusterheadache. In clinical studies, elevated levels of CGRP in the jugularvein were found to occur during migraine attacks (Goadsby et al. (1990)Ann. Neurol. 28, 183-187), salivary levels of CGRP are elevated inmigraine subjects between (Bellamy et al. (2006) Headache 46, 24-33) andduring attacks (Cady et al. (2009) Headache 49, 1258-1266), and CGRPitself has been shown to trigger migrainous headache (Lassen et al.(2002) Cephalalgia 22, 54-61). In clinical trials, the CGRP receptorantagonist BIBN4096BS has been shown to be effective in treating acuteattacks of migraine (Olesen et al. (2004) New Engl. J. Med. 350,1104-1110) and was able to prevent headache induced by CGRP infusion ina control group (Petersen et al. (2005) Clin. Pharmacol. Ther. 77,202-213). The orally bioavailable CGRP receptor antagonist telcagepanthas also shown antimigraine effectiveness in phase III clinical trials(Ho et al. (2008) Lancet 372, 2115-2123; Connor et al. (2009) Neurology73, 970-977).

CGRP-mediated activation of the trigeminovascular system may play a keyrole in migraine pathogenesis. Additionally, CGRP activates receptors onthe smooth muscle of intracranial vessels, leading to increasedvasodilation, which is thought to contribute to headache pain duringmigraine attacks (Lance, Headache Pathogenesis: Monoamines,Neuropeptides, Purines and Nitric Oxide, Lippincott-Raven Publishers,1997, 3-9). The middle meningeal artery, the principle artery in thedura mater, is innervated by sensory fibers from the trigeminal ganglionwhich contain several neuropeptides, including CGRP. Trigeminal ganglionstimulation in the cat resulted in increased levels of CGRP, and inhumans, activation of the trigeminal system caused facial flushing andincreased levels of CGRP in the external jugular vein (Goadsby et al.(1988) Ann. Neural. 23, 193-196). Electrical stimulation of the duramater in rats increased the diameter of the middle meningeal artery, aneffect that was blocked by prior administration of CGRP(8-37), a peptideCGRP receptor antagonist (Williamson et al. (1997) Cephalalgia 17,525-531). Trigeminal ganglion stimulation increased facial blood flow inthe rat, which was inhibited by CGRP(8-37) (Escott et al. (1995) BrainRes. 669, 93-99). Electrical stimulation of the trigeminal ganglion inmarmoset produced an increase in facial blood flow that could be blockedby the non-peptide CGRP receptor antagonist BIBN4096BS (Doods et al.(2000) Br. J. Pharmacol. 129, 420-423). Thus the vascular effects ofCGRP may be attenuated, prevented or reversed by a CGRP receptorantagonist.

CGRP-mediated vasodilation of rat middle meningeal artery was shown tosensitize neurons of the trigeminal nucleus caudalis (Williamson et al.,The CGRP Family: Calcitonin Gene-Related Peptide (CGRP), Amylin, andAdrenomedullin, Landes Bioscience, 2000, 245-247). Similarly, distentionof dural blood vessels during migraine headache may sensitize trigeminalneurons. Some of the associated symptoms of migraine, includingextra-cranial pain and facial allodynia, may be the result of sensitizedtrigeminal neurons (Burstein et al. (2000) Ann. Neural. 47, 614-624). ACGRP antagonist may be beneficial in attenuating, preventing orreversing the effects of neuronal sensitization.

The ability of the compounds of the present invention to act as CGRPreceptor antagonists makes them useful pharmacological agents fordisorders that involve CGRP in humans and animals, but particularly inhumans. Such disorders include migraine and cluster headache (Doods(2001) Curr. Opin. Invest. Drugs 2, 1261-1268; Edvinsson et al. (1994)Cephalalgia 14, 320-327); chronic tension type headache (Ashina et al.(2000) Neurology 14, 1335-1340); pain (Yu et al. (1998) Eur. J.Pharmacol. 347, 275-282); chronic pain (Hulsebosch et al. (2000) Pain86, 163-175); neurogenic inflammation and inflammatory pain (Holzer(1988) Neuroscience 24, 739-768; Delay-Goyet et al. (1992) Acta Physiol.Scanda. 146, 537-538; Salmon et al. (2001) Nature Neurosci. 4, 357-358);eye pain (May et al. (2002) Cephalalgia 22, 195-196), tooth pain(Awawdeh et al. (2002) Int. Endocrin. J 35, 30-36), non-insulindependent diabetes mellitus (Molina et al. (1990) Diabetes 39, 260-265);vascular disorders; inflammation (Zhang et al. (2001) Pain 89, 265);arthritis, bronchial hyperreactivity, asthma, (Foster et al. (1992) Ann.NY Acad. Sci. 657, 397-404; Schini et al. (1994) Am. J. Physiol. 267,H2483-H2490; Zheng et al. (1993) J. Viral. 67, 5786-5791); shock, sepsis(Beer et al. (2002) Crit. Care Med. 30, 1794-1798); opiate withdrawalsyndrome (Salmon et al. (2001) Nature Neurosci. 4, 357-358); morphinetolerance (Menard et al. (1996) J. Neurosci. 16, 2342-2351); hot flashesin men and women (Chen et al. (1993) Lancet 342, 49; Spetz et al. (2001)J. Urology 166, 1720-1723); allergic dermatitis (Wallengren (2000)Contact Dermatitis 43, 137-143); psoriasis; encephalitis, brain trauma,ischaemia, stroke, epilepsy, and neurodegenerative diseases (Rohrenbecket al. (1999) Neurobiol. Dis. 6, 15-34); skin diseases (Geppetti andHolzer, Eds., Neurogenic Inflammation, 1996, CRC Press, Boca Raton,Fla.), neurogenic cutaneous redness, skin rosaceousness and erythema;tinnitus (Herzog et al. (2002) J. Membr. Biol. 189, 225); obesity(Walker et al. (2010) Endocrinology 151, 4257-4269); inflammatory boweldisease, irritable bowel syndrome, (Hoffman et al. (2002) Scand. J.Gastroenterol. 37, 414-422) and cystitis. Of particular importance isthe acute or prophylactic treatment of headache, including migraine andcluster headache.

The present invention is directed to a class of highly potent CGRPreceptor antagonists, pharmaceutical compositions comprising them andtheir use in therapy.

SUMMARY OF THE INVENTION

The present invention is directed to piperidinone carboxamidespirohydantoin derivatives which are highly potent antagonists of CGRPreceptors and useful in the treatment or prevention of diseases in whichthe CGRP is involved, such as migraine. The invention is also directedto pharmaceutical compositions comprising these compounds and the use ofthese compounds and compositions in the prevention or treatment of suchdiseases in which CGRP is involved.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to a genus of compounds of Formula I:

or a pharmaceutically acceptable salt thereof, wherein:R¹ is selected from the group consisting of: C₁₋₄alkyl,cyclopropylmethyl, cyclobutylmethyl and[1-(trifluoromethyl)cyclopropyl]methyl, each of which is optionallysubstituted with one to four substituents as allowed by valenceindependently selected from the group consisting of: F and hydroxy;R² is hydrogen or methyl;when R² is hydrogen then

R³ is selected from hydrogen, F or Cl;

R⁴ is selected from hydrogen, F or Cl;

R⁵ is hydrogen;

R⁶ is selected from hydrogen or F; and

R⁷ is selected from hydrogen, F or Cl;

except that at least two of R³, R⁴, R⁶ and R⁷ must be F or Cl unless R³is F in which case R⁴, R⁶ and R⁷ may all be hydrogen; and if R⁴ is Clthen R⁷ cannot be Cl;

when R² is methyl then

R³ is selected from hydrogen, methyl, F, Cl, or Br;

R⁴ is selected from hydrogen, methyl, F or Cl;

R⁵ is selected from hydrogen or F;

R⁶ is selected from hydrogen or F; and

R⁷ is selected from hydrogen, methyl, F or Cl;

except that if R⁵ is F then at least three of R³, R⁴, R⁶ and R⁷ must beF; and if R⁴ is methyl or Cl then R⁷ cannot be methyl or Cl; and

R⁸ is selected from the group consisting of: hydrogen, C₁₋₄alkyl,cyclopropylmethyl, and cyclobutylmethyl, each of which is optionallysubstituted with one to three fluoro substituents as allowed by valence.

Within the genus, the invention encompasses a first sub-genus ofcompounds of Formula I, or a pharmaceutically acceptable salt thereof,wherein R¹ is C₁₋₄ alkyl, optionally substituted with one to foursubstituents as allowed by valence independently selected from the groupconsisting of F and hydroxy.

Within the first sub-genus, the invention encompasses a first class ofcompounds of Formula I, or a pharmaceutically acceptable salt thereof,wherein R¹ is selected from: isopropyl, 2,2,2-trifluoroethyl and2-methylpropyl.

Within the first class, the invention encompasses a first sub-class ofcompounds of Formula I, or a pharmaceutically acceptable salt thereof,wherein R¹ is 2,2,2-trifluoroethyl.

Also within the genus, the invention encompasses a second sub-genus ofcompounds of Formula I, or a pharmaceutically acceptable salt thereof,wherein R² is hydrogen.

Within the second sub-genus, the invention encompasses a second class ofcompounds of Formula I, or a pharmaceutically acceptable salt thereof,wherein at least two of R³, R⁴, R⁶ and R⁷ are F or Cl, except that if R⁴is Cl then R⁷ cannot be Cl.

Also within the second sub-genus, the invention encompasses a thirdclass of compounds of Formula I, or a pharmaceutically acceptable saltthereof, wherein R³ is F and R⁴, R⁶ and R⁷ are hydrogen.

Also within the genus, the invention encompasses a third sub-genus ofcompounds of Formula I, or a pharmaceutically acceptable salt thereof,wherein R² is methyl.

Within the third sub-genus, the invention encompasses a fourth class ofcompounds of Formula I, or a pharmaceutically acceptable salt thereof,wherein R⁵ is F and at least three of R³, R⁴, R⁶ and R⁷ are F.

Also within the third sub-genus, the invention encompasses a fifth classof compounds of Formula I, or a pharmaceutically acceptable saltthereof, wherein R⁵ is hydrogen and if R⁴ is methyl or Cl then R⁷ cannotbe methyl or Cl.

Also within the third sub-genus, the invention encompasses a sixth classof compounds of Formula I, or a pharmaceutically acceptable saltthereof, wherein R³ is selected from hydrogen, methyl or F; R⁴ isselected from hydrogen, methyl or F; R⁵ is hydrogen; R⁶ is selected fromhydrogen or F; and R⁷ is selected from hydrogen, methyl or F; exceptthat if R⁴ is methyl then R⁷ cannot be methyl. Within the sixth class,the invention encompasses a second sub-class of compounds of Formula I,or a pharmaceutically acceptable salt thereof, wherein R³ is hydrogen orF, R⁴ is hydrogen or F, R⁶ is hydrogen or F, and R⁷ is hydrogen or F.

Also within the third sub-genus, the invention encompasses a seventhclass of compounds of Formula I, or a pharmaceutically acceptable saltthereof, wherein R⁸ is C₁₋₄alkyl. Within the seventh class, theinvention encompasses a third sub-class of compounds of Formula I, or apharmaceutically acceptable salt thereof, wherein R⁸ is methyl.

Also within the genus, the invention encompasses a fourth sub-genus ofcompounds of Formula I, or a pharmaceutically acceptable salt thereof,wherein R⁸ is C₁₋₄alkyl. Within the fourth sub-genus, the inventionencompasses an eighth class of compounds of Formula I, or apharmaceutically acceptable salt thereof, wherein R⁸ is methyl.

The invention also encompasses a compound selected from the followingtable:

R² Ar Me 2,3,5-trifluorophenyl Me 2,3,6-trifluorophenyl Me2,3,5,6-tetrafluorophenylor a pharmaceutically acceptable salt thereof.

The invention also encompasses a pharmaceutical composition whichcomprises an inert carrier and the compound of Formula I, or apharmaceutically acceptable salt thereof.

The invention also encompasses a method of treating headache in amammalian patient in need of such treatment, which comprisesadministering to the patient a therapeutically effective amount of thecompound of Formula I, or a pharmaceutically acceptable salt thereof. Ina specific embodiment of the invention, the headache is migraineheadache.

The invention also encompasses the use of a compound of Formula I, or apharmaceutically acceptable salt thereof, and a pharmaceuticallyacceptable carrier, for the manufacture of a medicament for thetreatment of headache. In a specific embodiment of the invention, theheadache is migraine headache.

The invention is also directed to medicaments or pharmaceuticalcompositions for treating diseases or disorders in which CGRP isinvolved, such as migraine, which comprise a compound of Formula I, or apharmaceutically acceptable salt thereof, and a pharmaceuticallyacceptable carrier.

The invention is also directed to the use of a compound of Formula I fortreating diseases or disorders in which CGRP is involved, such asmigraine.

The invention is further directed to a method for the manufacture of amedicament or a composition for treating diseases or disorders in whichCGRP is involved, such as migraine, comprising combining a compound ofFormula I with one or more pharmaceutically acceptable carriers.

As is appreciated by one skilled in the art, the following structuresdepict the same stereochemistry:

The above structures are used interchangeably in the application and arewell understood in the art to represent the same stereochemistry. Also,the substitution on the nitrogen above is sometime depicted as a bond,and other times as “Me”. Both are well understood to mean a methylsubstitution.

The compounds of the present invention may contain one or moreasymmetric centers and can thus occur as racemates and racemic mixtures,single enantiomers, diastereomeric mixtures and individualdiastereomers. Additional asymmetric centers may be present dependingupon the nature of the various substituents on the molecule. Each suchasymmetric center will independently produce two optical isomers and itis intended that all of the possible optical isomers and diastereomersin mixtures and as pure or partially purified compounds are includedwithin the ambit of this invention. Unless a specific stereochemistry isindicated, the present invention is meant to comprehend all suchisomeric forms of these compounds.

The independent syntheses of these diastereomers or theirchromatographic separations may be achieved as known in the art byappropriate modification of the methodology disclosed herein. Theirabsolute stereochemistry may be determined by the x-ray crystallographyof crystalline products or crystalline intermediates which arederivatized, if necessary, with a reagent containing an asymmetriccenter of known absolute configuration.

If desired, racemic mixtures of the compounds may be separated so thatthe individual enantiomers are isolated. The separation can be carriedout by methods well known in the art, such as the coupling of a racemicmixture of compounds to an enantiomerically pure compound to form adiastereomeric mixture, followed by separation of the individualdiastereomers by standard methods, such as fractional crystallization orchromatography. The coupling reaction is often the formation of saltsusing an enantiomerically pure acid or base. The diasteromericderivatives may then be converted to the pure enantiomers by cleavage ofthe added chiral residue. The racemic mixture of the compounds can alsobe separated directly by chromatographic methods utilizing chiralstationary phases, which methods are well known in the art.

Alternatively, any enantiomer of a compound may be obtained bystereoselective synthesis using optically pure starting materials orreagents of known configuration by methods well known in the art.

In the compounds of Formula I, the atoms may exhibit their naturalisotopic abundances, or one or more of the atoms may be artificiallyenriched in a particular isotope having the same atomic number, but anatomic mass or mass number different from the atomic mass or mass numberpredominantly found in nature. The present invention is meant to includeall suitable isotopic variations of the compounds of generic Formula I.For example, different isotopic forms of hydrogen (H) include protium(¹H) and deuterium (²H). Protium is the predominant hydrogen isotopefound in nature. Enriching for deuterium may afford certain therapeuticadvantages, such as increasing in vivo half-life or reducing dosagerequirements, or may provide a compound useful as a standard forcharacterization of biological samples. Isotopically-enriched compoundswithin generic Formula I can be prepared without undue experimentationby conventional techniques well known to those skilled in the art or byprocesses analogous to those described in the Schemes and Examplesherein using appropriate isotopically-enriched reagents and/orintermediates.

Tautomers of compounds defined in Formula I are also included within thescope of the present invention. For example, compounds includingcarbonyl —CH₂C(O)— groups (keto forms) may undergo tautomerism to formhydroxyl —CH═C(OH)— groups (enol forms). Both keto and enol forms areincluded within the scope of the present invention.

As used herein, “alkyl” is intended to mean linear or branchedstructures having no carbon-to-carbon double or triple bonds. Thus,C₁₋₄alkyl is defined to identify the group as having 1, 2, 3 or 4carbons in a linear or branched arrangement, such that C₁₋₄alkylspecifically includes, but is not limited to, methyl, ethyl, n-propyl,iso-propyl, n-butyl, iso-butyl and tert-butyl.

As is well understood by one having ordinary skill in the art, “F” meansfluoro, “Cl” means chloro and “Br” means bromo.

The phrase “pharmaceutically acceptable” is employed herein to refer tothose compounds, materials, compositions, and/or dosage forms which are,within the scope of sound medical judgment, suitable for use in contactwith the tissues of human beings and animals without excessive toxicity,irritation, allergic response, or other problem or complication,commensurate with a reasonable benefit/risk ratio.

As used herein, “pharmaceutically acceptable salts” refer to derivativeswherein the parent compound is modified by making acid or base saltsthereof. Salts in the solid form may exist in more than one crystalstructure, and may also be in the form of hydrates. Examples ofpharmaceutically acceptable salts include, but are not limited to,mineral or organic acid salts of basic residues such as amines; alkalior organic salts of acidic residues such as carboxylic acids; and thelike. The pharmaceutically acceptable salts include the conventionalnon-toxic salts or the quaternary ammonium salts of the parent compoundformed, for example, from non-toxic inorganic or organic acids. Forexample, such conventional non-toxic salts include those derived frominorganic acids such as hydrochloric, hydrobromic, sulfuric, sulfamic,phosphoric, nitric and the like; and the salts prepared from organicacids such as acetic, propionic, succinic, glycolic, stearic, lactic,malic, tartaric, citric, ascorbic, pamoic, maleic, hydroxymaleic,phenylacetic, glutamic, benzoic, salicylic, sulfanilic,2-acetoxybenzoic, fumaric, toluenesulfonic, methanesulfonic, ethanedisulfonic, oxalic, isethionic, and the like. Salts derived frominorganic bases include aluminum, ammonium, calcium, copper, ferric,ferrous, lithium, magnesium, manganic salts, manganous, potassium,sodium, zinc, and the like.

When the compound of the present invention is basic, salts may beprepared from pharmaceutically acceptable non-toxic acids, includinginorganic and organic acids. Such acids include acetic, benzenesulfonic,benzoic, camphorsulfonic, citric, ethanesulfonic, fumaric, gluconic,glutamic, hydrobromic, hydrochloric, isethionic, lactic, maleic, malic,mandelic, methanesulfonic, mucic, nitric, pamoic, pantothenic,phosphoric, succinic, sulfuric, tartaric, p-toluenesulfonic acid, andthe like. In one aspect of the invention the salts are citric,hydrobromic, hydrochloric, maleic, phosphoric, sulfuric, fumaric, andtartaric acids. It will be understood that, as used herein, referencesto the compounds of Formula I are meant to also include thepharmaceutically acceptable salts.

Exemplifying the invention is the use of the compounds disclosed in theExamples and herein. Specific compounds within the present inventioninclude a compound which may be selected from the group consisting ofthe compounds disclosed in the following Examples and pharmaceuticallyacceptable salts thereof and individual diastereomers thereof.

The subject compounds are useful in a method of antagonism of CGRPreceptors in a patient such as a mammal in need of such antagonismcomprising the administration of an effective amount of the compound.The present invention is directed to the use of the compounds disclosedherein as antagonists of CGRP receptors. In addition to primates,especially humans, a variety of other mammals can be treated accordingto the method of the present invention.

Another embodiment of the present invention is directed to a method forthe treatment, control, amelioration, or reduction of risk of a diseaseor disorder in which the CGRP receptor is involved in a patient thatcomprises administering to the patient a therapeutically effectiveamount of a compound that is an antagonist of CGRP receptors.

The present invention is further directed to a method for themanufacture of a medicament for antagonism of CGRP receptors activity inhumans and animals comprising combining a compound of the presentinvention with a pharmaceutical carrier or diluent.

The subject treated in the present methods is generally a mammal, forexample a human being, male or female, in whom antagonism of CGRPreceptor activity is desired. The term “therapeutically effectiveamount” means the amount of the subject compound that will elicit thebiological or medical response of a tissue, system, animal or human thatis being sought by the researcher, veterinarian, medical doctor or otherclinician. As used herein, the term “treatment” refers both to thetreatment and to the prevention or prophylactic therapy of the mentionedconditions, particularly in a patient who is predisposed to such diseaseor disorder.

The term “composition” as used herein is intended to encompass a productcomprising the specified ingredients in the specified amounts, as wellas any product which results, directly or indirectly, from combinationof the specified ingredients in the specified amounts. Such term inrelation to pharmaceutical composition, is intended to encompass aproduct comprising the active ingredient(s), and the inert ingredient(s)that make up the carrier, as well as any product which results, directlyor indirectly, from combination, complexation or aggregation of any twoor more of the ingredients, or from dissociation of one or more of theingredients, or from other types of reactions or interactions of one ormore of the ingredients. Accordingly, the pharmaceutical compositions ofthe present invention encompass any composition made by admixing acompound of the present invention and a pharmaceutically acceptablecarrier. By “pharmaceutically acceptable” it is meant the carrier,diluent or excipient must be compatible with the other ingredients ofthe formulation and not deleterious to the recipient thereof.

The present invention includes within its scope prodrugs of thecompounds of this invention. In general, such prodrugs will befunctional derivatives of the compounds of this invention which arereadily convertible in vivo into the required compound. Thus, in themethods of treatment of the present invention, the terms “administrationof” or “administering a” compound shall encompass the treatment of thevarious conditions described with the compound specifically disclosed orwith a compound which may not be specifically disclosed, but whichconverts to the specified compound in vivo after administration to thepatient. Conventional procedures for the selection and preparation ofsuitable prodrug derivatives are described, for example, in “Design ofProdrugs,” ed. H. Bundgaard, Elsevier, 1985. Metabolites of thesecompounds include active species produced upon introduction of compoundsof this invention into the biological milieu.

The ability of the compounds of the present invention to act as CGRPreceptor antagonists makes them useful pharmacological agents fordisorders that involve CGRP in humans and animals, but particularly inhumans.

The compounds of the present invention have utility in treating,preventing, ameliorating, controlling or reducing the risk of one ormore of the following conditions or diseases: headache; migraine;cluster headache; chronic tension type headache; pain; chronic pain;neurogenic inflammation and inflammatory pain; neuropathic pain; eyepain; tooth pain; diabetes; non-insulin dependent diabetes mellitus;vascular disorders; inflammation; arthritis; bronchial hyperreactivity,asthma; shock; sepsis; opiate withdrawal syndrome; morphine tolerance;hot flashes in men and women; allergic dermatitis; psoriasis;encephalitis; brain trauma; epilepsy; neurodegenerative diseases; skindiseases; neurogenic cutaneous redness, skin rosaceousness and erythema;obesity; inflammatory bowel disease, irritable bowel syndrome, cystitis;and other conditions that may be treated or prevented by antagonism ofCGRP receptors. Of particular importance is the acute or prophylactictreatment of headache, including migraine and cluster headache.

The subject compounds are further useful in a method for the prevention,treatment, control, amelioration, or reduction of risk of the diseases,disorders and conditions noted herein.

The subject compounds are further useful in a method for the prevention,treatment, control, amelioration, or reduction of risk of theaforementioned diseases, disorders and conditions in combination withother agents.

The compounds of the present invention may be used in combination withone or more other drugs in the treatment, prevention, control,amelioration, or reduction of risk of diseases or conditions for whichcompounds of Formula I or the other drugs may have utility, where thecombination of the drugs together are safer or more effective thaneither drug alone. Such other drug(s) may be administered, by a routeand in an amount commonly used therefor, contemporaneously orsequentially with a compound of Formula I. When a compound of Formula Iis used contemporaneously with one or more other drugs, a pharmaceuticalcomposition in unit dosage form containing such other drugs and thecompound of Formula I is preferred. However, the combination therapy mayalso include therapies in which the compound of Formula I and one ormore other drugs are administered on different overlapping schedules. Itis also contemplated that when used in combination with one or moreother active ingredients, the compounds of the present invention and theother active ingredients may be used in lower doses than when each isused singly. Accordingly, the pharmaceutical compositions of the presentinvention include those that contain one or more other activeingredients, in addition to a compound of Formula I.

For example, the present compounds may be used in conjunction with ananti-migraine agent, such as ergotamine and dihydroergotamine, or otherserotonin agonists, especially a 5-HT_(1B/1D) agonist, for examplesumatriptan, naratriptan, zolmitriptan, eletriptan, almotriptan,frovatriptan, donitriptan, and rizatriptan, a 5-HT_(1D) agonist such asPNU-142633 and a 5-HT_(1F) agonist such as LY334370; a cyclooxygenaseinhibitor, such as a selective cyclooxygenase-2 inhibitor, for examplerofecoxib, etoricoxib, celecoxib, valdecoxib or paracoxib; anon-steroidal anti-inflammatory agent or a cytokine-suppressinganti-inflammatory agent, for example with a compound such as ibuprofen,ketoprofen, fenoprofen, naproxen, indomethacin, sulindac, meloxicam,piroxicam, tenoxicam, lornoxicam, ketorolac, etodolac, mefenamic acid,meclofenamic acid, flufenamic acid, tolfenamic acid, diclofenac,oxaprozin, apazone, nimesulide, nabumetone, tenidap, etanercept,tolmetin, phenylbutazone, oxyphenbutazone, diflunisal, salsalate,olsalazine or sulfasalazine and the like; or glucocorticoids. Similarly,the instant compounds may be administered with an analgesic such asaspirin, acetaminophen, phenacetin, fentanyl, sufentanil, methadone,acetyl methadol, buprenorphine or morphine.

Additionally, the present compounds may be used in conjunction with aninterleukin inhibitor, such as an interleukin-1 inhibitor; an NK-1receptor antagonist, for example aprepitant; an NMDA antagonist; an NR2Bantagonist; a bradykinin-1 receptor antagonist; an adenosine A1 receptoragonist; a sodium channel blocker, for example lamotrigine; an opiateagonist such as levomethadyl acetate or methadyl acetate; a lipoxygenaseinhibitor, such as an inhibitor of 5-lipoxygenase; an alpha receptorantagonist, for example indoramin; an alpha receptor agonist; avanilloid receptor antagonist; a renin inhibitor; a granzyme Binhibitor; a substance P antagonist; an endothelin antagonist; anorepinephrin precursor; anti-anxiety agents such as diazepam,alprazolam, chlordiazepoxide and chlorazepate; serotonin 5HT₂ receptorantagonists; opiod agonists such as codeine, hydrocodone, tramadol,dextropropoxyphene and febtanyl; an mGluR5 agonist, antagonist orpotentiator; a GABA A receptor modulator, for example acamprosatecalcium; nicotinic antagonists or agonists including nicotine;muscarinic agonists or antagonists; a selective serotonin reuptakeinhibitor, for example fluoxetine, paroxetine, sertraline, duloxetine,escitalopram, or citalopram; an antidepressant, for exampleamitriptyline, nortriptyline, clomipramine, imipramine, venlafaxine,doxepin, protriptyline, desipramine, trimipramine, or imipramine; aleukotriene antagonist, for example montelukast or zafirlukast; aninhibitor of nitric oxide or an inhibitor of the synthesis of nitricoxide.

Also, the present compounds may be used in conjunction with gap junctioninhibitors; neuronal calcium channel blockers such as civamide; AMPA/KAantagonists such as LY293558; sigma receptor agonists; and vitamin B2.

Also, the present compounds may be used in conjunction with ergotalkaloids other than ergotamine and dihydroergotamine, for exampleergonovine, ergonovine, methylergonovine, metergoline, ergoloidmesylates, dihydroergocornine, dihydroergocristine, dihydroergocryptine,dihydro-α-ergocryptine, dihydro-β-ergocryptine, ergotoxine, ergocornine,ergocristine, ergocryptine, α-ergocryptine, β-ergocryptine, ergosine,ergostane, bromocriptine, or methysergide.

Additionally, the present compounds may be used in conjunction with abeta-adrenergic antagonist such as timolol, propanolol, atenolol,metoprolol or nadolol, and the like; a MAO inhibitor, for examplephenelzine; a calcium channel blocker, for example flunarizine,diltiazem, amlodipine, felodipine, nisolipine, isradipine, nimodipine,lomerizine, verapamil, nifedipine, or prochlorperazine; neurolepticssuch as olanzapine, droperidol, prochlorperazine, chlorpromazine andquetiapine; an anticonvulsant such as topiramate, zonisamide,tonabersat, carabersat, levetiracetam, lamotrigine, tiagabine,gabapentin, pregabalin or divalproex sodium; an anti-hypertensive suchas an angiotensin II antagonist, for example losartan, irbesartin,valsartan, eprosartan, telmisartan, olmesartan, medoxomil, candesartanand candesartan cilexetil, an angiotensin I antagonist, an angiotensinconverting enzyme inhibitor such as lisinopril, enalapril, captopril,benazepril, quinapril, perindopril, ramipril and trandolapril; orbotulinum toxin type A or B.

The present compounds may be used in conjunction with a potentiator suchas caffeine, an H2-antagonist, simethicone, aluminum or magnesiumhydroxide; a decongestant such as oxymetazoline, epinephrine,naphazoline, xylometazoline, propylhexedrine, or levo-desoxy-ephedrine;an antitussive such as caramiphen, carbetapentane, or dextromethorphan;a diuretic; a prokinetic agent such as metoclopramide or domperidone; asedating or non-sedating antihistamine such as acrivastine, azatadine,bromodiphenhydramine, brompheniramine, carbinoxamine, chlorpheniramine,clemastine, dexbrompheniramine, dexchlorpheniramine, diphenhydramine,doxylamine, loratadine, phenindamine, pheniramine, phenyltoloxamine,promethazine, pyrilamine, terfenadine, triprolidine, phenylephrine,phenylpropanolamine, or pseudoephedrine. The present compounds also maybe used in conjunction with anti-emetics.

In an embodiment of the invention the present compounds are used inconjunction with an anti-migraine agent, such as: ergotamine ordihydroergotamine; a 5-HT₁ agonist, especially a 5-HT_(1B/1D) agonist,in particular, sumatriptan, naratriptan, zolmitriptan, eletriptan,almotriptan, frovatriptan, donitriptan, avitriptan and rizatriptan, andother serotonin agonists; and a cyclooxygenase inhibitor, such as aselective cyclooxygenase-2 inhibitor, in particular, rofecoxib,etoricoxib, celecoxib, valdecoxib or paracoxib.

The above combinations include combinations of a compound of the presentinvention not only with one other active compound, but also with two ormore other active compounds. Likewise, compounds of the presentinvention may be used in combination with other drugs that are used inthe prevention, treatment, control, amelioration, or reduction of riskof the diseases or conditions for which compounds of the presentinvention are useful. Such other drugs may be administered, by a routeand in an amount commonly used therefore, contemporaneously orsequentially with a compound of the present invention. When a compoundof the present invention is used contemporaneously with one or moreother drugs, a pharmaceutical composition containing such other drugs inaddition to the compound of the present invention is preferred.Accordingly, the pharmaceutical compositions of the present inventioninclude those that also contain one or more other active ingredients, inaddition to a compound of the present invention.

The weight ratio of the compound of the compound of the presentinvention to the other active ingredient(s) may be varied and willdepend upon the effective dose of each ingredient. Generally, aneffective dose of each will be used. Thus, for example, when a compoundof the present invention is combined with another agent, the weightratio of the compound of the present invention to the other agent willgenerally range from about 1000:1 to about 1:1000, or from about 200:1to about 1:200. Combinations of a compound of the present invention andother active ingredients will generally also be within theaforementioned range, but in each case, an effective dose of each activeingredient should be used.

In such combinations the compound of the present invention and otheractive agents may be administered separately or in conjunction. Inaddition, the administration of one element may be prior to, concurrentto, or subsequent to the administration of other agent(s), and via thesame or different routes of administration.

The compounds of the present invention may be administered by oral,parenteral (e.g., intramuscular, intraperitoneal, intravenous, ICV,intracisternal injection or infusion, subcutaneous injection, orimplant), by inhalation spray, nasal, vaginal, rectal, sublingual,buccal or topical routes of administration and may be formulated, aloneor together, in suitable dosage unit formulations containingconventional non-toxic pharmaceutically acceptable carriers, adjuvantsand vehicles appropriate for each route of administration. In additionto the treatment of warm-blooded animals the compounds of the inventionare effective for use in humans.

The pharmaceutical compositions for the administration of the compoundsof this invention may conveniently be presented in dosage unit form andmay be prepared by any of the methods well known in the art of pharmacy.All methods include the step of bringing the active ingredient intoassociation with the carrier which constitutes one or more accessoryingredients. In general, the pharmaceutical compositions are prepared byuniformly and intimately bringing the active ingredient into associationwith a liquid carrier or a finely divided solid carrier or both, andthen, if necessary, shaping the product into the desired formulation. Inthe pharmaceutical composition the active compound is included in anamount sufficient to produce the desired effect upon the process orcondition of diseases. As used herein, the term “composition” isintended to encompass a product comprising the specified ingredients inthe specified amounts, as well as any product which results, directly orindirectly, from combination of the specified ingredients in thespecified amounts.

The pharmaceutical compositions containing the active ingredient may bein a form suitable for oral use, for example, as tablets, troches,lozenges, aqueous or oily suspensions, dispersible powders or granules,emulsions, solutions, hard or soft capsules, or syrups or elixirs.Compositions intended for oral use may be prepared according to anymethod known to the art for the manufacture of pharmaceuticalcompositions and such compositions may contain one or more agentsselected from the group consisting of sweetening agents, flavoringagents, coloring agents and preserving agents in order to providepharmaceutically elegant and palatable preparations. Tablets contain theactive ingredient in admixture with non-toxic pharmaceuticallyacceptable excipients which are suitable for the manufacture of tablets.These excipients may be for example, inert diluents, such as calciumcarbonate, sodium carbonate, lactose, calcium phosphate or sodiumphosphate; granulating and disintegrating agents, for example, cornstarch, or alginic acid; binding agents, for example starch, gelatin oracacia; and lubricating agents, for example magnesium stearate, stearicacid or talc. The tablets may be uncoated or they may be coated by knowntechniques to delay disintegration and absorption in thegastrointestinal tract and thereby provide a sustained action over alonger period. For example, a time delay material such as glycerylmonostearate or glyceryl distearate may be employed. They may also becoated by the techniques described in the U.S. Pat. Nos. 4,256,108;4,166,452; and 4,265,874 to form osmotic therapeutic tablets for controlrelease. Oral tablets may also be formulated for immediate release, suchas fast melt tablets or wafers, rapid dissolve tablets or fast dissolvefilms.

Formulations for oral use may also be presented as hard gelatin capsuleswherein the active ingredient is mixed with an inert solid diluent, forexample, calcium carbonate, calcium phosphate or kaolin, or as softgelatin capsules wherein the active ingredient is mixed with water or anoil medium, for example peanut oil, liquid paraffin, or olive oil.

Aqueous suspensions contain the active materials in admixture withexcipients suitable for the manufacture of aqueous suspensions. Suchexcipients are suspending agents, for example sodiumcarboxymethylcellulose, methylcellulose, hydroxy-propylmethylcellulose,sodium alginate, polyvinyl-pyrrolidone, gum tragacanth and gum acacia;dispersing or wetting agents may be a naturally-occurring phosphatide,for example lecithin, or condensation products of an alkylene oxide withfatty acids, for example polyoxyethylene stearate, or condensationproducts of ethylene oxide with long chain aliphatic alcohols, forexample heptadecaethyleneoxycetanol, or condensation products ofethylene oxide with partial esters derived from fatty acids and ahexitol such as polyoxyethylene sorbitol monooleate, or condensationproducts of ethylene oxide with partial esters derived from fatty acidsand hexitol anhydrides, for example polyethylene sorbitan monooleate.The aqueous suspensions may also contain one or more preservatives, forexample ethyl, or n-propyl, p-hydroxybenzoate, one or more coloringagents, one or more flavoring agents, and one or more sweetening agents,such as sucrose or saccharin.

Oily suspensions may be formulated by suspending the active ingredientin a vegetable oil, for example arachis oil, olive oil, sesame oil orcoconut oil, or in a mineral oil such as liquid paraffin. The oilysuspensions may contain a thickening agent, for example beeswax, hardparaffin or cetyl alcohol. Sweetening agents such as those set forthabove, and flavoring agents may be added to provide a palatable oralpreparation. These compositions may be preserved by the addition of ananti-oxidant such as ascorbic acid.

Dispersible powders and granules suitable for preparation of an aqueoussuspension by the addition of water provide the active ingredient inadmixture with a dispersing or wetting agent, suspending agent and oneor more preservatives. Suitable dispersing or wetting agents andsuspending agents are exemplified by those already mentioned above.Additional excipients, for example sweetening, flavoring and coloringagents, may also be present.

The pharmaceutical compositions of the invention may also be in the formof oil-in-water emulsions. The oily phase may be a vegetable oil, forexample olive oil or arachis oil, or a mineral oil, for example liquidparaffin or mixtures of these. Suitable emulsifying agents may benaturally-occurring gums, for example gum acacia or gum tragacanth,naturally-occurring phosphatides, for example soy bean, lecithin, andesters or partial esters derived from fatty acids and hexitolanhydrides, for example sorbitan monooleate, and condensation productsof the said partial esters with ethylene oxide, for examplepolyoxyethylene sorbitan monooleate. The emulsions may also containsweetening and flavoring agents.

Syrups and elixirs may be formulated with sweetening agents, for exampleglycerol, propylene glycol, sorbitol or sucrose. Such formulations mayalso contain a demulcent, a preservative and flavoring and coloringagents.

The pharmaceutical compositions may be in the form of a sterileinjectable aqueous or oleagenous suspension. This suspension may beformulated according to the known art using those suitable dispersing orwetting agents and suspending agents which have been mentioned above.The sterile injectable preparation may also be a sterile injectablesolution or suspension in a non-toxic parenterally-acceptable diluent orsolvent, for example as a solution in 1,3-butane diol. Among theacceptable vehicles and solvents that may be employed are water,Ringer's solution and isotonic sodium chloride solution. In addition,sterile, fixed oils are conventionally employed as a solvent orsuspending medium. For this purpose any bland fixed oil may be employedincluding synthetic mono- or diglycerides. In addition, fatty acids suchas oleic acid find use in the preparation of injectables.

The compounds of the present invention may also be administered in theform of suppositories for rectal administration of the drug. Thesecompositions can be prepared by mixing the drug with a suitablenon-irritating excipient which is solid at ordinary temperatures butliquid at the rectal temperature and will therefore melt in the rectumto release the drug. Such materials are cocoa butter and polyethyleneglycols.

For topical use, creams, ointments, jellies, solutions or suspensionsand the like, containing the compounds of the present invention areemployed. Similarly, transdermal patches may also be used for topicaladministration.

The pharmaceutical composition and method of the present invention mayfurther comprise other therapeutically active compounds as noted hereinwhich are usually applied in the treatment of the above mentionedpathological conditions.

In the treatment, prevention, control, amelioration, or reduction ofrisk of conditions which require antagonism of CGRP receptor activity anappropriate dosage level will generally be about 0.01 to 500 mg per kgpatient body weight per day which can be administered in single ormultiple doses. A suitable dosage level may be about 0.01 to 250 mg/kgper day, about 0.05 to 100 mg/kg per day, or about 0.1 to 50 mg/kg perday. Within this range the dosage may be 0.05 to 0.5, 0.5 to 5 or 5 to50 mg/kg per day. For oral administration, the compositions are may beprovided in the form of tablets containing 1.0 to 1000 milligrams of theactive ingredient, particularly 1.0, 5.0, 10.0, 15.0. 20.0, 25.0, 50.0,75.0, 100.0, 150.0, 200.0, 250.0, 300.0, 400.0, 500.0, 600.0, 750.0,800.0, 900.0, and 1000.0 milligrams of the active ingredient for thesymptomatic adjustment of the dosage to the patient to be treated. Thecompounds may be administered on a regimen of 1 to 4 times per day, ormay be administered once or twice per day.

When treating, preventing, controlling, ameliorating, or reducing therisk of headache, migraine, cluster headache, or other diseases forwhich compounds of the present invention are indicated, generallysatisfactory results are obtained when the compounds of the presentinvention are administered at a daily dosage of from about 0.1 milligramto about 100 milligram per kilogram of animal body weight, given as asingle daily dose or in divided doses two to six times a day, or insustained release form. For most large mammals, the total daily dosageis from about 1.0 milligrams to about 1000 milligrams, or from about 1milligrams to about 50 milligrams. In the case of a 70 kg adult human,the total daily dose will generally be from about 7 milligrams to about350 milligrams. This dosage regimen may be adjusted to provide theoptimal therapeutic response.

It will be understood, however, that the specific dose level andfrequency of dosage for any particular patient may be varied and willdepend upon a variety of factors including the activity of the specificcompound employed, the metabolic stability and length of action of thatcompound, the age, body weight, general health, sex, diet, mode and timeof administration, rate of excretion, drug combination, the severity ofthe particular condition, and the host undergoing therapy.

The utility of the compounds in accordance with the present invention asantagonists of CGRP receptor activity may be demonstrated by methodologyknown in the art. Inhibition of the binding of ¹²⁵I-CGRP to receptorsand functional antagonism of CGRP receptors were determined as follows:

NATIVE RECEPTOR BINDING ASSAY: The binding of ¹²⁵I-CGRP to receptors inSK-N-MC cell membranes was carried out essentially as described(Edvinsson et al. (2001) Eur. J. Pharmacol. 415, 39-44). Briefly,membranes (25 μg) were incubated in 1 mL of binding buffer [10 mM HEPES,pH 7.4, 5 mM MgCl₂ and 0.2% bovine serum albumin (BSA)] containing 10 pM¹²⁵I-CGRP and antagonist. After incubation at room temperature for 3 h,the assay was terminated by filtration through GFB glass fibre filterplates (PerkinElmer) that had been blocked with 0.5% polyethyleneiminefor 3 h. The filters were washed three times with ice-cold assay buffer(10 mM HEPES, pH 7.4 and 5 mM MgCl₂), then the plates were air dried.Scintillation fluid (50 μL) was added and the radioactivity was countedon a Topcount (Packard Instrument). Data analysis was carried out byusing Prism and the K_(i) was determined by using the Cheng-Prusoffequation (Cheng & Prusoff (1973) Biochem. Pharmacol. 22, 3099-3108).

RECOMBINANT RECEPTOR: Human CL receptor (Genbank accession numberL76380) was subcloned into the expression vector pIREShyg2 (BDBiosciences Clontech) as a 5′NheI and 3′ PmeI fragment. Human RAMP1(Genbank accession number AJ001014) was subcloned into the expressionvector pIRESpuro2 (BD Biosciences Clontech) as a 5′NheI and 3′NotIfragment. HEK 293 cells (human embryonic kidney cells; ATCC #CRL-1573)were cultured in DMEM with 4.5 g/L glucose, 1 mM sodium pyruvate and 2mM glutamine supplemented with 10% fetal bovine serum (FBS), 100units/mL penicillin and 100 μg/mL streptomycin, and maintained at 37° C.and 95% humidity. Cells were subcultured by treatment with 0.25% trypsinwith 0.1% EDTA in HBSS. Stable cell line generation was accomplished byco-transfecting 10 μg of DNA with 30 μg Lipofectamine 2000 (Invitrogen)in 75 cm² flasks. CL receptor and RAMP1 expression constructs wereco-transfected in equal amounts. Twenty-four hours after transfectionthe cells were diluted and selective medium (growth medium+300 μg/mLhygromycin and 1 μg/mL puromycin) was added the following day. A clonalcell line was generated by single cell deposition utilizing a FACSVantage SE (Becton Dickinson). Growth medium was adjusted to 150 μg/mLhygromycin and 0.5 μg/mL puromycin for cell propagation.

RECOMBINANT RECEPTOR BINDING ASSAY: Cells expressing recombinant humanCL receptor/RAMP1 were washed with PBS and harvested in harvest buffercontaining 50 mM HEPES, 1 mM EDTA and Complete™ protease inhibitors(Roche). The cell suspension was disrupted with a laboratory homogenizerand centrifuged at 48,000 g to isolate membranes. The pellets wereresuspended in harvest buffer plus 250 mM sucrose and stored at −70° C.For binding assays, 20 μg of membranes were incubated in 1 mL bindingbuffer (10 mM HEPES, pH 7.4, 5 mM MgCl₂, and 0.2% BSA) for 3 h at roomtemperature containing 10 pM ¹²⁵I-hCGRP (GE Healthcare) and antagonist.The assay was terminated by filtration through 96-well GFB glass fiberfilter plates (PerkinElmer) that had been blocked with 0.05%polyethyleneimine. The filters were washed 3 times with ice-cold assaybuffer (10 mM HEPES, pH 7.4, and 5 mM MgCl₂). Scintillation fluid wasadded and the plates were counted on a Topcount (Packard). Non-specificbinding was determined and the data analysis was carried out with theapparent dissociation constant (K₁) determined by using a non-linearleast squares fitting the bound CPM data to the equation below:

$Y_{obsd} = \frac{\begin{matrix}{{\left( {Y_{\max} - Y_{\min}} \right)\left( {{\%\mspace{14mu} I_{\max}} - {\%_{1\min}/100}} \right)} +} \\{Y_{\min} + {\left( {Y_{\max} - Y_{\min}} \right)\left( {100 - {\%\mspace{14mu}{I_{\max}/100}}} \right)}}\end{matrix}}{1 + \left( {\lbrack{Drug}\rbrack/{K_{i}\left( {1 + {\left\lbrack {{Radio}\;{label}} \right\rbrack/K_{d}}} \right)}^{nH}} \right.}$Where Y is observed CPM bound, Y_(max) is total bound counts, Y_(min) isnon specific bound counts, (Y_(max)−Y_(min)) is specific bound counts, %I_(max) is the maximum percent inhibition, % 1 min is the minimumpercent inhibition, radiolabel is the probe, and the K_(d) is theapparent dissociation constant for the radioligand for the receptor asdetermined by hot saturation experiments.

RECOMBINANT RECEPTOR FUNCTIONAL ASSAY: Cells were resuspended inDMEM/F12 (Hyclone) supplemented with 1 g/L BSA and 300 μMisobutyl-methylxanthine. Cells were then plated in a 384-well plate(Proxiplate Plus 384; 509052761; Perkin-Elmer) at a density of 2,000cells/well and incubated with antagonist for 30 min at 37° C. Humanα-CGRP was then added to the cells at a final concentration of 1.2 nMand incubated an additional 20 min at 37° C. Following agoniststimulation, the cells were processed for cAMP determination using thetwo-step procedure according to the manufacturer's recommended protocol(HTRF cAMP dynamic 2 assay kit; 62AM4PEC; Cisbio). Raw data weretransformed into concentration of cAMP using a standard curve then doseresponse curves were plotted and inflection point (IP) values weredetermined.

Exemplary K_(i) values in the recombinant receptor binding assay forexemplary compounds of the invention are provided in the table below:

Example K_(i) (nM) 1 0.061 2 0.059 3 0.28The following abbreviations are used throughout the text:

-   -   Me: methyl    -   Et: ethyl    -   t-Bu: tert-butyl    -   Bu: butyl    -   i-Pr: isopropyl    -   Ar: aryl    -   Ph: phenyl    -   Bn: benzyl    -   Py: pyridyl    -   Ac: acetylate    -   OAc: acetate    -   DCE: 1,2-dichloroethane    -   TFA: trifluoroacetic acid    -   TEA: triethylamine    -   Boc: tert-butoxycarbonyl    -   BOP: (Benzotriazol-1-yloxy)tris(dimethylamino)phosphonium        hexafluorophosphate    -   DIEA: N,N-diisopropylethylamine    -   HOBT: 1-hydroxybenzotriazole    -   EDC: N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide        hydrochloride    -   PyCIU: chlorodipyrrolidinocarbenium    -   n-BuLi: n-butyllithium    -   HATU: O-(7-azabenzotriazol-1-yl)-N,N,N′,N′-tetramethyluronium        hexafluorophosphate    -   EDTA: ethylenediaminetetraacetic acid    -   DMF: N,N-dimethylformamide    -   HMDS: hexamethyldisilazane    -   THF: tetrahydrofuran    -   DMSO: dimethylsulfoxide    -   SEM: 2-trimethylsilylethoxymethyl    -   SEMCl: 2-trimethylsilylethoxymethyl chloride    -   PBPB: pyridinium bromide perbromide    -   DMEM: Dulbecco's Modified Eagle Medium (High Glucose)    -   FBS: fetal bovine serum    -   BSA: bovine serum albumin    -   PBS: phosphate-buffered saline    -   HEPES: N-(2-hydroxyethyl)piperazine-N′-(2-ethanesulfonic acid)    -   min: minutes    -   h: hours    -   aq: aqueous    -   HPLC: high performance liquid chromatography    -   LCMS: liquid chromatography-mass spectrometry    -   SFC: supercritical fluid chromatography    -   MTBE: tert-butyl methyl ether    -   NMP: 1-methyl-2-pyrrolidinone    -   trisyl: 2,4,6-triisopropylbenzenesulfonyl    -   CAN: ammonium cerium(IV) nitrate    -   dppf: 1,1′-bis(diphenylphosphino)ferrocene    -   Ra Ni: Raney®-Nickel

Methods for preparing the compounds of this invention are illustrated inthe following Schemes and Examples. Starting materials are madeaccording to procedures known in the art or as illustrated herein.

The compounds of the present invention can be prepared readily accordingto the following Schemes and specific examples, or modificationsthereof, using readily available starting materials, reagents andconventional synthesis procedures. In these reactions, it is alsopossible to make use of variants which are themselves known to those ofordinary skill in this art but are not mentioned in greater detail. Thegeneral procedures for making the compounds claimed in this inventioncan be readily understood and appreciated by one skilled in the art fromviewing the following Schemes.

While the invention has been described and illustrated with reference tocertain particular embodiments thereof, those skilled in the art willappreciate that various adaptations, changes, modifications,substitutions, deletions, or additions of procedures and protocols maybe made without departing from the spirit and scope of the invention.For example, effective dosages other than the particular dosages as setforth herein above may be applicable as a consequence of variations inthe responsiveness of the mammal being treated for any of theindications with the compounds of the invention indicated above.Likewise, the specific pharmacological responses observed may varyaccording to and depending upon the particular active compounds selectedor whether there are present pharmaceutical carriers, as well as thetype of formulation and mode of administration employed, and suchexpected variations or differences in the results are contemplated inaccordance with the objects and practices of the present invention. Itis intended, therefore, that the invention be defined by the scope ofthe claims which follow and that such claims be interpreted as broadlyas is reasonable.

REACTION SCHEMES

The compounds of the present invention can be prepared readily accordingto the following Schemes and specific examples, or modificationsthereof, using readily available starting materials, reagents andconventional synthetic procedures. In these reactions, it is alsopossible to make use of variants which are themselves known to those ofordinary skill in this art but are not mentioned in greater detail. Thegeneral procedures for making the compounds claimed in this inventioncan be readily understood and appreciated by one skilled in the art fromviewing the following Schemes.

Scheme 1 illustrates a route to 3-aminopiperidinone intermediates oftype 1.5 which may be used to prepare compounds of the presentinvention. Aryl acetone 1.1 can be alkylated using iodoalaninederivative 1.2 under basic conditions to provide keto ester 1.3.Reductive amination followed by cyclization and epimerization providesprimarily cis-substituted lactam 1.4 as a racemic mixture. Chiralresolution using normal-phase liquid chromatography, for example, andremoval of the Boc protecting group under acidic conditions furnishes3-aminopiperidinone 1.5 as a hydrochloride salt.

A synthetic route to 3-aminopiperidinone intermediates of type 2.4 isshown in Scheme 2. Aryl acetonitrile 2.1 can be alkylated usingiodoalanine derivative 1.2 under basic conditions to provide cyano ester2.2. Reductive cyclization using hydrogen and palladium hydroxide oncarbon or Raney nickel, epimerization, and chiral resolution affords thecis-substituted lactam 2.3 as a single enantiomer. N-Alkylation andremoval of the Boc protecting group then provides 2.4 as a hydrochloridesalt.

Scheme 3 illustrates an alternative route to 3-aminopiperidinoneintermediates of type 2.4. The arylacetonitrile 3.1 may be condensedwith acrylate 3.2 at elevated temperature to give the 4-cyanobutanoateester 3.3. Hydrogenation of nitrile 3.3 using Raney nickel catalyst andan ethanolic solution of ammonia affords the corresponding amineproduct, which typically cyclizes in situ to provide piperidinone 3.4.N-Alkylation of lactam 3.4 may be accomplished by a variety of methodsknown to those skilled in the art of organic synthesis, the exact choiceof conditions being influenced by the nature of the alkylating agent,R¹X. Electrophilic azidation of the resulting substituted lactam 3.5 canbe accomplished using similar methodology to that described by Evans andcoworkers (Evans et al. (1990) J. Am. Chem. Soc. 112, 4011-4030) toprovide the azide 3.6 as a mixture of diastereoisomers, which can beseparated by chromatography. The desired cis diastereomer of azide 3.6may be reduced by catalytic hydrogenation in the presence ofdi-tert-butyl dicarbonate to give the corresponding Boc-protected amine3.7, and separation of the enantiomers using chiral HPLC or SFC leads tothe (3S,5S)-isomer 3.8. Finally, standard deprotection affords thedesired 3-aminopiperidinone intermediates 2.4.

Another approach to 3-aminopiperidinone intermediates of interest, whichis particularly useful for preparing3-amino-6-methyl-5-arylpiperidin-2-ones such as 1.5, is outlined inScheme 4. The pyridinone 4.1 may be converted to the N-substitutedpyridinone 4.2 by treatment with a suitable electrophile (R¹X) underbasic conditions. Pyridinone 4.2 can then be subjected to Suzukicoupling with the boronic acid 4.3, and the resulting 5-arylpyridinone4.4 may be hydrogenated using, for example, platinum(IV) oxide catalystto afford the corresponding 5-arylpiperidinone 4.5, which is usuallyobtained as predominantly the cis isomer. Further elaboration ofpiperidinone 4.5 may be achieved using analogous methodology to thatdescribed in Scheme 6. Specifically, electrophilic azidation followed byone-pot reduction and Boc protection leads to carbamate 4.7, and thedesired enantiomer may be obtained using chiral chromatography. In somecases, the desired diastereomer of azide 4.6 may be isolated as aracemic mixture of the (3S,5S,6R)- and (3R,5R,6S)-isomers followingsilica gel chromatography of the crude product, and this mixture may beelaborated as outlined in Scheme 7. In other cases, it may beadvantageous to take a mixture of diastereomers of azide 4.6 forward tothe corresponding carbamate 4.7. The mixture of carbamate 4.7diastereomers may be epimerized under basic conditions, such aspotassium carbonate in EtOH, to afford a mixture that is significantlyenriched in the desired (3S,5S,6R)- and (3R,5R,6S)-isomers, furtherpurification may be employed to obtain the enantiomer of interest asoutlined herein.

Methodology for synthesizing spirohydantoin intermediates that may beused to prepare the compounds of the present invention is outlined inScheme 5. Following a one-pot esterification-bromination ofpyridine-2,3-dicarboxylic acid (5.1), reduction of the resulting diester5.2 affords diol 5.3. The imide functionality of 1-methylhydantoin (5.4)may be protected, for example with a 4-methoxybenzyl group, to give a1,3-dialkylated hydantoin such as 5.5. Other protecting groups may alsobe employed as alternatives to 4-methoxybenzyl. Diol 5.3 can beconverted to the corresponding dichloride 5.6 using thionyl chloride,and 5.6 may be reacted with hydantoin 5.5 using sodium hydride as baseto provide the spirohydantoin intermediate 5.7. Bromide 5.7 can beconverted to the corresponding methyl ester 5.8 via palladium-catalyzedcarbonylation as shown, and deprotection followed by saponificationaffords the racemic carboxylic acid 5.10. This route may be modified toprovide the individual enantiomers of acid 5.10. For example, theracemic ester 5.8 may be separated using chiral SFC to provide (R)-5.8and (S)-5.8, and these individual enantiomers may be deprotected inanalogy with Scheme 5 to provide 5.10 as its individual enantiomers.

Scheme 6 illustrates conditions that can be used for the coupling of3-aminopiperidinone intermediates, such as 6.1, and carboxylic acidintermediate 6.2, to produce, in this instance, amides 6.3. Thesestandard coupling conditions are representative of the methods used toprepare the compounds of the present invention.

In some cases, various protecting group strategies familiar to oneskilled in the art of organic synthesis may be employed to allowpreparation of a particular compound of the present invention.

It is understood that alternative methodologies may also be employed inthe synthesis of these key intermediates. For instance, racemic reactionsequences may be utilized, followed by chiral separations at appropriatesteps to provide compounds of the present invention. The exact choice ofreagents, solvents, temperatures, and other reaction conditions, dependsupon the nature of the intended product. In some cases, appropriateprotecting group strategies may be used.

In some cases the final product may be further modified, for example, bymanipulation of substituents. These manipulations may include, but arenot limited to, reduction, oxidation, alkylation, acylation, andhydrolysis reactions which are commonly known to those skilled in theart.

In some cases the order of carrying out the foregoing reaction schemesmay be varied to facilitate the reaction or to avoid unwanted reactionproducts. Additionally, various protecting group strategies may beemployed to facilitate the reaction or to avoid unwanted reactionproducts. The following examples are provided so that the inventionmight be more fully understood. These examples are illustrative only andshould not be construed as limiting the invention in any way.

INTERMEDIATE 1

3′Methyl-2′,5′-dioxo-5,7-dihydrospiro[cyclopenta[b]pyridine-6,4′-imidazolidine]-3-carboxylicacid Step A: Dimethyl 5-bromopyridine-2,3-dicarboxylate

Concentrated sulfuric acid (1 L, 18.7 mol) was added slowly over 10 minto a suspension of pyridine-2,3-dicarboxylic acid (5.00 kg, 29.9 mol) inmethanol (50 L), dissolving the suspension. The resulting mixture washeated at reflux for 48 h then cooled to 40° C. Bromine (8.0 kg, 50 mol)was added slowly over 2 h in 1-kg portions, keeping the temperaturebelow 55° C. The reaction mixture was then heated at 55° C. for 24 h,cooled to 50° C. and additional Br₂ (4.0 kg, 25 mol) was added slowlyover 1 h in 1-kg portions, keeping temperature below 55° C. The reactionmixture was heated at 55° C. for 24 h, concentrated to a minimum volume(internal temp ˜30° C., solution may occasionally foam), then dilutedwith isopropyl acetate (50 L) and washed with a saturated aqueous sodiumsulfite solution (3×20 L) (final extract is ˜pH 8) followed by water (20L). The organic layer was concentrated to approximately 15 L thendiluted with heptane (40 L). The resulting slurry was stirred for 24 hat 23° C. The solids were filtered, washed with heptane (10 L), anddried to give the title compound.

Step B: (5-Bromopyridine-2,3-diyl)dimethanol

Sodium borohydride (15.9 g, 420 mmol) was added portionwise over 30minutes to a solution of dimethyl 5-bromopyridine-2,3-dicarboxylate (20g, 73 mmol) in ethanol (460 mL) precooled to 0° C. A solution of calciumchloride (23.3 g, 209 mmol) in ethanol (150 mL) was added slowly at 0°C., and the reaction mixture was warmed to 23° C. and stirred overnight.Excess sodium borohydride was quenched by slow addition of aqueous 2 NHCl solution (230 mL, 460 mmol), followed by a stirring at 23° C. for 2h. The mixture was concentrated to dryness. Saturated aqueous sodiumbicarbonate solution was added to the residue until a pH ofapproximately 7 was reached. The aqueous mixture was extracted with2-methyltetrahydrofuran (4×200 mL). The combined organic layers weredried over sodium sulfate then treated with a solution of 4 N HCl indioxane (25 mL, 100 mmol). The resulting solid was filtered, washed with2-methyltetrahydrofuran, and dried to give the title compound as ahydrochloride salt. MS: m/z=218.1 (M+1).

Step C: 5-Bromo-2,3-bis(chloromethyl)pyridine

To a solution of (5-bromopyridine-2,3-diyl)dimethanol (5.0 g, 22.9 mmol)in DMF (230 mL) at ambient temperature was added thionyl chloride (5.59g, 47.0 mmol). The mixture was warmed to 35° C. and stirred for 18 hbefore partitioning between aqueous sodium bicarbonate (500 mL) and MTBE(500 mL). The organic was washed with water (2×250 mL), dried oversodium sulfate, filtered, and concentrated to provide the titlecompound. MS: m/z=253.9 (M+1).

Step D: 3-(4-Methoxybenzyl)-1-methylimidazolidine-2,4-dione

To a stirring solution of 1-methylhydantoin (40.0 g, 351 mmol) in DMF(700 mL) at ambient temperature was added 4-methoxybenzyl chloride (49.4g, 316 mmol) and cesium carbonate (171 g, 526 mmol). The resultingmixture was stirred for 3 days, then partitioned between H₂O (2 L) andEtOAc (800 mL). The aqueous layer was extracted further with EtOAc (500mL) and the combined organic extracts were washed with H₂O (2×300 mL),dried over sodium sulfate, filtered, and concentrated in vacuo. Theresulting white precipitate was collected by vacuum filtration andwashed with MTBE (200 mL) to provide the title compound. MS: m/z=235.2(M+1).

Step E:3-Bromo-1′-(4-methoxybenzyl)-3′-methyl-5,7-dihydro-2′H,5′H-spiro[cyclopenta[b]pyridine-6,4′-imidazolidine]-2′,5′-dione

To a solution of 3-(4-methoxybenzyl)-1-methylimidazolidine-2,4-dione(4.50 g, 19.2 mmol) in 1:1-THF:DMPU (190 mL) at 0° C. was added NaH(1.60 g, 40.4 mmol). After 10 min, a solution of5-bromo-2,3-bis(chloromethyl)pyridine (4.90 g, 19.2 mmol) in THF (10 mL)was added dropwise, and the reaction mixture was allowed to warm to 10°C. over 1 h. To the reaction mixture was added H₂O (10 mL) dropwise, andthe resulting mixture was partitioned between H₂O (500 mL) and EtOAc(500 mL). The aqueous layer was extracted further with EtOAc (3×200 mL)and the combined organic extracts were dried over sodium sulfate,filtered, and concentrated in vacuo. The crude product was purified bysilica gel chromatography, eluting with a gradient ofheptane:EtOAc—80:20 to 20:80, to give the title compound. MS: m/z=415.9(M+1).

Step F: Methyl1′-(4-methoxybenzyl)-3′-methyl-2′,5′-dioxo-5,7-dihydrospiro[cyclopenta[b]pyridine-6,4′-imidazolidine]-3-carboxylate

To a solution of3-bromo-1′-(4-methoxybenzyl)-3′-methyl-5,7-dihydro-2′H,5′H-spiro[cyclopenta[b]pyridine-6,4′-imidazolidine]-2′,5′-dione(500 mg, 1.2 mmol) in MeOH (12 mL) was added sodium acetate (296 mg, 3.6mmol) and PdCl₂(dppf).CH₂Cl₂ (196 mg, 0.24 mmol). The resulting mixturewas charged in a high-pressure Parr cell which was evacuated and thenpurged with nitrogen (3×). After the final evacuation the vessel waspressurized with CO to 300 psi. The stirred mixture was heated at 80° C.for 3 days, then diluted with EtOAc (50 mL) and filtered through a plugof silica gel, washing with EtOAc. The filtrate was concentrated invacuo and the crude product was purified by silica gel chromatography,eluting with a gradient of heptane:EtOAc—90:10 to 0:100, to give thetitle compound. MS: m/z=396.0 (M+1).

Step G: Methyl3′-methyl-2′,5′-dioxo-5,7-dihydrospiro[cyclopenta[b]pyridine-6,4′-imidazolidine]-3-carboxylate

To a solution of methyl1′-(4-methoxybenzyl)-3′-methyl-2′,5′-dioxo-5,7-dihydrospiro[cyclopenta[b]pyridine-6,4′-imidazolidine]-3-carboxylate(100 mg, 0.25 mmol) in acetonitrile (8.4 mL) at ambient temperature wasadded eerie ammonium nitrate (4.1 g, 7.6 mmol) as a solution in H₂O (5mL). After 20 min, the reaction mixture was partitioned between H₂O (50mL) and 9:1—CH₂Cl₂:i-PrOH (50 mL). The aqueous was extracted furtherwith 9:1—CH₂Cl₂:i-PrOH (5×50 mL) and the combined organic extracts weredried over sodium sulfate, filtered, and concentrated in vacuo. Thecrude solid was washed with MTBE (3×10 mL) then partitioned betweensaturated aqueous sodium bicarbonate (5 mL) and EtOAc (10 mL). Theaqueous layer was extracted further with EtOAc (10 mL) and the combinedorganic extracts were dried over sodium sulfate, filtered, andconcentrated in vacuo to provide the title compound in sufficient purityfor use in the next step. MS: m/z 276.1 (M+1).

Step H:3′-Methyl-2′,5′-dioxo-5,7-dihydrospiro[cyclopenta[b]pyridine-6,4′-imidazolidine]-3-carboxylicacid

To a solution of methyl3′-methyl-2′,5′-dioxo-5,7-dihydrospiro[cyclopenta[b]pyridine-6,4′-imidazolidine]-3-carboxylate(25 mg, 0.091 mmol) in THF (0.5 mL) and H₂O (0.3 mL) was added 1 Naqueous lithium hydroxide (0.27 mL, 0.27 mmol). The reaction was stirredat ambient temperature for 1 h, acidified by addition of 1 Nhydrochloric acid, and concentrated in vacuo to provide the titlecompound. MS: m/z=262.1 (M+1). ¹H NMR (500 MHz, CDCl₃) δ 8.99 (s, 1H),8.31 (s, 1H), 3.55 (m, 2H), 3.44 (d, 1H, J=18.3 Hz), 3.42 (d, 1H, J=17.6Hz), 2.72 (s, 3H).

INTERMEDIATE 2

(3S,5S,6R)-3-Amino-6-methyl-5-phenyl-1-(2,2,2-trifluoroethyl)piperidin-2-oneStep A: Methyl2[(tert-butoxycarbonyl)amino]-4-(3-chlorophenyl)-5-oxohexanoate

A mixture of cesium carbonate (9.80 g, 30.1 mmol) and methylN-(tert-butoxycarbonyl)-3-iodo-D-alaninate (9.90 g, 30.1 mmol) in DMF(75 mL) was stirred at 23° C. for 45 min before1-(3-chlorophenyl)propan-2-one (6.09 g, 36.1 mmol) and additional cesiumcarbonate (9.80 g, 30.1 mmol) were added. The resulting mixture wasstirred for 2.5 h. The majority of the DMF was then removed underreduced pressure at a bath temperature of <40° C. The concentratedmixture was partitioned between water (500 mL) and ethyl acetate (2×200mL). The combined organic layers were washed with brine, dried oversodium sulfate and concentrated to give the title compound as a 1:1racemic mixture of diastereomers, which was used without furtherpurification. MS: m/z=314.1 (M−t-Bu+1).

Step B:tert-Butyl[(3S,5S,6R)-5-(3-chlorophenyl)-6-methyl-2-oxo-1-(2,2,2-trifluoroethyl)piperidin-3-yl]carbamate

A slurry of methyl2-[(tert-butoxycarbonyl)amino]-4-(3-chlorophenyl)-5-oxohexanoate as a1:1 racemic mixture of diastereomers (11.1 g, 30.0 mmol),2,2,2-trifluoroethylamine (9.59 mL, 120 mmol), acetic acid (10.3 mL, 180mmol), sodium triacetoxyborohydride (25.4 g, 120 mmol), and flame-dried4 Å molecular sieves (50 g) in 1,2-dichloroethane (300 mL) was stirredat 23° C. for 8 h. Additional 2,2,2-trifluoroethylamine (9.59 mL, 120mmol), acetic acid (10.3 mL, 180 mmol), and sodium triacetoxyborohydride(25.4 g, 120 mmol) were added and stirring was continued for 20 h. Thereaction mixture was diluted with dichloromethane (200 mL) then pouredinto water (500 mL). Molecular sieves were removed by filtration, andthe organic layer was washed with water (3×500 mL), dried over sodiumsulfate, and concentrated. A solution of the residue in ethanol (200 mL)was stirred in the presence of solid potassium carbonate (12.4 g, 90mmol) at 60° C. for 2 h, then 23° C. for 16 h. The bulk of the ethanolwas removed under reduced pressure and the remaining slurry was thenpartitioned between water (500 mL) and ethyl acetate (300 mL). Theorganic layer was washed with brine, dried over sodium sulfate andconcentrated. The residue was crystallized from 2:1 mixture of hexaneand ethyl ether to give the title compound as a racemate. Theenantiomers were separated using normal-phase HPLC using a ChiralPak® ADcolumn and eluting with 40% hexane in ethanol initially, stepping to 20%hexane in ethanol (0.1% diethylamine used as a modifier) to afford thetitle compound as the second enantiomer to elute. MS: m/z=421.2 (M+1).

Step C:(3S,5S,6R)-3-Amino-6-methyl-5-phenyl-1-(2,2,2-trifluoroethyl)piperidin-2-one

A mixture of tert-butyl[(3S,5S,6R)-5-(3-chlorophenyl)-6-methyl-2-oxo-1-(2,2,2-trifluoroethyl)piperidin-3-yl]carbamate(2.75 g, 6.53 mmol) and 20 wt. % palladium hydroxide on carbon (˜50 wt.% wet, 700 mg, 0.50 mmol) in methanol (100 mL) was stirred under ahydrogen balloon at 23° C. for 16 h. The catalyst was removed byfiltration through a pad of Celite® and washed thoroughly with methanoland ethyl acetate. Following concentration of the filtrate, a solutionof the residue in ethyl acetate (100 mL) pre-cooled to 0° C. was spargedwith HCl gas for ˜1 min. The ice-bath was removed and the acidicsolution was allowed to warm to 23° C. as stirring was continued for 2h. The mixture was then concentrated to dryness to afford the titlecompound as a hydrochloride salt. HRMS: m/z=287.1361, calculated m/z287.1366 for C₁₄H₁₈F₃N₂O. ¹H NMR (500 MHz, CD₃OD) δ 7.39 (t, 2H, J=7.3Hz), 7.31 (t, 1H, J=7.3 Hz), 7.27 (d, 2H, J=7.3 Hz), 4.81-4.73 (m, 1H),4.24 (dd, 1H, J=12.0, 6.8 Hz), 3.94 (p, 1H, J=6.0 Hz), 3.76-3.67 (m,2H), 2.56 (q, 1H, J=12.7 Hz), 2.42 (m, 1H), 1.00 (d, 3H, J=6.3 Hz).

INTERMEDIATE 3

(3S,5S)-3-Amino-5-(2,2,2-difluorophenyl)-1-(2,2,2-trifluoroethyl)piperidin-2-onehydrochloride Step A: Ethyl 4-cyano-4-(2,3-difluorophenyl)butanoate

To a mixture of (2,3-difluorophenyl)acetonitrile (40.5 g, 265 mmol),ethyl acrylate (24 mL, 221 mmol), and hydroquinone (50 mg, 0.45 mmol)was added KOH (2 M in MeOH, 2.0 mL, 4.0 mmol) and the resulting mixturewas heated at 160° C. for 16 h and then allowed to cool to ambienttemperature. The crude mixture was purified by silica gelchromatography, eluting with a gradient of hexanes:EtOAc—100:0 to 50:50,to give the title compound. MS: m/z=207.9 (M−OEt).

Step B: 5-(2,3-Difluorophenyl)piperidin-2-one

A mixture of ethyl 4-cyano-4-(2,3-difluorophenyl)butanoate (18.52 g,73.1 mmol), Raney nickel (slurry in water, ca. 30 g), and ammonia (2M inEtOH, 550 mL) was stirred vigorously under an atmosphere of hydrogen(ca. 1 atm) for 18 h. The reaction mixture was filtered through a pad ofCelite®, washing with EtOH, and the filtrate was concentrated in vacuoto give a crude solid. Recrystallization from EtOAc afforded the titlecompound. MS: m/z=211.9 (M+1).

Step C: 5-(2,3-Difluorophenyl)-1-(2,2,2-trifluoroethyl)piperidin-2-one

To a stirred solution of 5-(2,3-difluorophenyl)piperidin-2-one (8.88 g,42 mmol) in THF (250 mL) and NMP (170 mL) at 0° C. was added lithiumbis(trimethylsilyl)amide (1.0 M in THF, 48 mL, 48 mmol) over 5 min,keeping the internal temperature of the reaction mixture below 5° C. Theresulting mixture was stirred at 0° C. for 15 min, then2,2,2-trifluoroethyl triflate (11.2 g, 48 mmol) was added dropwise,keeping the internal temperature of the reaction mixture below 5° C. Thereaction mixture was allowed to warm slowly to ambient temperature andstirring was continued for 3 h. The resulting mixture was partitionedbetween saturated aqueous sodium bicarbonate (800 mL) and EtOAc (1 L).The organic layer was removed and the aqueous phase was extractedfurther with EtOAc (500 mL). The combined organic extracts were washedwith water, then brine, then dried over sodium sulfate, filtered, andconcentrated to dryness in vacuo. The crude product was purified bysilica gel chromatography, eluting with a gradient ofhexanes:EtOAc—100:0 to 0:100, to give the title compound. MS: m/z=293.9(M+1).

Step D: (3R,5R &3S,5S)-3-Azido-5-(2,3-difluorophenyl)-1-(2,2,2-trifluoroethyl)piperidin-2-one

To a stirred solution of lithium bis(trimethylsilyl)amide (1.0 M in THF,26.3 mL, 26.3 mmol) in THF (120 mL) at −78° C. was added a cold (−78°C.) solution of5-(2,3-difluorophenyl)-1-(2,2,2-trifluoroethyl)piperidin-2-one (6.42 g,21.9 mmol) in THF (100 mL) dropwise, keeping the internal temperature ofthe reaction mixture below −65° C. The resulting mixture was stirred at−78° C. for 30 min, then a cold (−78° C.) solution of2,4,6-triisopropylbenzenesulfonyl azide (Harmon et al. J. Org. Chem.1973, 38, 11-16) (8.81 g, 28.5 mmol) in THF (80 mL) was added dropwise,keeping the internal temperature of the reaction mixture below −65° C.The reaction mixture was stirred at −78° C. for 45 min, then AcOH (6.0mL, 105 mmol) was added. The resulting mixture was allowed to warmslowly to ambient temperature and was partitioned between saturatedaqueous sodium bicarbonate (1 L) and CH₂Cl₂ (1.5 L). The organic layerwas washed with brine, then dried over sodium sulfate, filtered, andconcentrated to dryness in vacuo. The crude product was purified bysilica gel chromatography, eluting with a gradient ofhexanes:EtOAc—100:0 to 40:60, to give the title compound. MS: m/z=334.9(M+1).

Step E: tert-Butyl[(3S,5S)-5-(2,3-difluorophenyl)-2-oxo-1-(2,2,2-trifluoroethyl)piperidin-3-yl]carbamate

To a mixture of (3R,5R &3S,5S)-3-azido-5-(2,3-difluorophenyl)-1-(2,2,2-trifluoroethyl)piperidin-2-one(6.14 g, 18.4 mmol) and di-tert-butyl dicarbonate (4.81 g, 22.0 mmol) inEtOH (160 mL) was added 10% palladium on carbon (0.98 g, 0.92 mmol) andthe resulting mixture was stirred vigorously under an atmosphere ofhydrogen (ca. 1 atm) for 18 h. The reaction mixture was filtered througha pad of Celite®, washing with EtOH, and the filtrate was concentratedin vacuo to give a crude solid. The crude product was purified by silicagel chromatography, eluting with a gradient of CH₂Cl₂:EtOAc—100:0 to60:40, to give the racemic product. Separation of the enantiomers wasachieved by HPLC on a ChiralPak® AD column, eluting withEtOH:hexanes:Et₂NH—60:40:0.04, to give tert-butyl[(3R,5R)-5-(2,3-difluorophenyl)-2-oxo-1-(2,2,2-trifluoroethyl)piperidin-3-yl]carbamateas the first major peak, and tert-butyl[(3S,5S)-5-(2,3-difluorophenyl)-2-oxo-1-(2,2,2-trifluoroethyl)piperidin-3-yl]carbamate,the title compound, as the second major peak. MS: m/z=431.0 (M+Na).

Step F:(3S,5S)-3-Amino-5-(2,3-difluorophenyl)-1-(2,2,2-trifluoroethyl)piperidin-2-onehydrochloride

A solution of tert-butyl[(3S,5S)-5-(2,3-difluorophenyl)-2-oxo-1-(2,2,2-trifluoroethyl)piperidin-3-yl]carbamate(1.50 g, 3.67 mmol) in EtOAc (30 mL) at 0° C. was saturated with HCl (g)and aged for 30 min. The resulting mixture was concentrated in vacuo togive the title compound. MS: m/z=309.0 (M+1); ¹H NMR (500 MHz, CD₃OD) δ7.29-7.17 (m, 3H), 4.36-4.25 (m, 2H), 4.12 (dq, 1H, J=15.1, 9.3 Hz),3.84 (m, 1H), 3.75 (ddd, 1H, J=12.0, 5.4, 1.7 Hz), 3.64 (t, 1H, J=11.6Hz), 2.46 (m, 1H), 2.37 (q, 1H, J=12.2 Hz).

INTERMEDIATE 4

(3S,5S,6R)-3-Amino-6-methyl-1-(2,2,2-trifluoroethyl)-5-(2,3,5-trifluorophenyl)piperidin-2-onehydrochloride Step A:5-Bromo-6-methyl-1-(2,2,2-trifluoroethyl)pyridin-2(1H)-one

To a stirred mixture of 3-bromo-6-hydroxy-2-methylpyridine (25.0 g, 133mmol) and cesium carbonate (52.0 g, 160 mmol) in 1,4-dioxane (600 mL)was added 2,2,2-trifluoroethyl triflate (40.1 g, 173 mmol) and theresulting mixture was heated at 50° C. for 4 h and then allowed to coolto ambient temperature. The resulting mixture was filtered and thefiltrate was concentrated to dryness in vacuo. The crude product waspurified by silica gel chromatography, eluting with a gradient ofCH₂Cl₂:EtOAc—100:0 to 60:40, to give the title compound. MS: m/z=269.9(M+1).

Step B:6-Methyl-1-(2,2,2-trifluoroethyl)-5-(2,3,5-trifluorophenyl)pyridin-2(1H)-one

Argon was bubbled through a stirred solution of5-bromo-6-methyl-1-(2,2,2-trifluoroethyl)pyridin-2(1H)-one (9.43 g, 34.9mmol) in THF (280 mL) for 15 min. To this solution were added2,3,5-trifluorophenylboronic acid (12.3 g, 69.8 mmol), then cesiumfluoride (10.6 g, 69.8 mmol), and finallybis(tri-tert-butylphosphine)palladium(0) (892 mg, 1.75 mmol), and argonwas bubbled through the mixture for 5 min after each addition. Thereaction mixture was stirred at ambient temperature for 90 min and wasthen partitioned between saturated aqueous sodium bicarbonate (500 mL)and EtOAc (600 mL). The organic layer was removed and the aqueous phasewas extracted further with EtOAc (300 mL). The combined organic extractswere washed with brine, then dried over sodium sulfate, filtered, andconcentrated to dryness in vacuo. The crude product was purified bysilica gel chromatography, eluting with a gradient ofhexanes:EtOAc—100:0 to 0:100, to give the title compound. MS: m/z=322.0(M+1).

Step C: (5S,6R &5R,6S)-6-Methyl-1-(2,2,2-trifluoroethyl)-5-(2,3,5-trifluorophenyl)piperidin-2-one

A mixture of6-methyl-1-(2,2,2-trifluoroethyl)-5-(2,3,5-trifluorophenyl)pyridin-2(1H)-one(3.73 g, 11.6 mmol) and platinum(IV) oxide (659 mg, 2.90 mmol) in MeOH(200 mL) was shaken on a Parr hydrogenation apparatus under anatmosphere of hydrogen (ca. 45 psi) for 2 h. The reaction mixture wasfiltered through a pad of Celite®, washing with MeOH, and the filtratewas concentrated in vacuo to give a crude solid. The crude product waspurified by silica gel chromatography, eluting with a gradient ofhexanes:Et₂O—100:0 to 0:100, to give the title compound. MS: m/z=326.0(M+1).

Step D: (5S,6R &5R,6S)-3-Azido-6-methyl-1-(2,2,2-trifluoroethyl)-5-(2,3,5-trifluorophenyl)piperidin-2-one

To a stirred solution of lithium bis(trimethylsilyl)amide (1.0 M in THF,36 mL, 36 mmol) in THF (180 mL) at −78° C. was added a cold (−78° C.)solution of (5S,6R &5R,6S)-6-methyl-1-(2,2,2-trifluoroethyl)-5-(2,3,5-trifluorophenyl)piperidin-2-one(9.68 g, 29.8 mmol) in THF (100+20 mL) dropwise, keeping the internaltemperature of the reaction mixture below −65° C. The resulting mixturewas stirred at −78° C. for 30 min, then a cold (−78° C.) solution of2,4,6-triisopropylbenzenesulfonyl azide (Harmon et al. (1973) J. Org.Chem. 38, 11-16) (11.97 g, 38.7 mmol) in THF (100 mL) was addeddropwise, keeping the internal temperature of the reaction mixture below−65° C. The reaction mixture was stirred at −78° C. for 45 min, thenAcOH (7.8 mL, 137 mmol) was added. The resulting mixture was allowed towarm slowly to ambient temperature and was poured into saturated aqueoussodium bicarbonate (750 mL) and the mixture was extracted with CH₂Cl₂(2×750 mL). The combined organic layers were washed with brine, thendried over sodium sulfate, filtered, and concentrated to dryness invacuo. The crude product was purified by silica gel chromatography,eluting with a gradient of hexanes:Et₂O—100:0 to 0:100, to give thetitle compound. MS: m/z=367.1 (M+1).

Step E: tert-Butyl [(5S,6R &5R,6S)-6-methyl-2-oxo-1-(2,2,2-trifluoroethyl)-5-(2,3,5-trifluorophenyl)piperidin-3-yl]carbamate

To a mixture of (5S,6R &5R,6S)-3-azido-6-methyl-1-(2,2,2-trifluoroethyl)-5-(2,3,5-trifluorophenyl)piperidin-2-one(1.80 g, 4.91 mmol) and di-text-butyl dicarbonate (1.18 g, 5.41 mmol) inEtOH (30 mL) was added 10% palladium on carbon (200 mg, 0.19 mmol) andthe resulting mixture was stirred vigorously under an atmosphere ofhydrogen (ca. 1 atm) for 1 h. The reaction mixture was filtered througha pad of Celite®, washing with EtOH, and the filtrate was concentratedin vacuo to give a crude solid. The crude product was purified by silicagel chromatography, eluting with a gradient of hexanes:EtOAc—100:0 to30:70, to give the title compound. MS: m/z=463.2 (M+Na).

Step F: tert-Butyl[(3S,5S,6R)-6-methyl-2-oxo-1-(2,2,2-trifluoroethyl)-5-(2,3,5-trifluorophenyl)piperidin-3-yl]carbamate

To a stirred solution of tert-butyl [(5S,6R &5R,6S)-6-methyl-2-oxo-1-(2,2,2-trifluoroethyl)-5-(2,3,5-trifluorophenyl)piperidin-3-yl]carbamate(4.90 g, 11.1 mmol) in EtOH (100 mL) was added potassium carbonate (3.84g, 27.8 mmol) and the resulting mixture was heated at 50° C. for 2 h.The reaction mixture was allowed to cool to ambient temperature andconcentrated in vacuo to a volume of ca. 30 mL. The concentrated mixturewas poured into saturated aqueous sodium bicarbonate (75 mL) and themixture was extracted with EtOAc (2×125 mL). The combined organic layerswere dried over sodium sulfate, filtered, and concentrated to dryness invacuo. The crude product was purified by silica gel chromatography,eluting with a gradient of hexanes:EtOAc—100:0 to 0:100, to give theracemic product. Separation of the enantiomers was achieved by HPLC on aChiralPak® AD column, eluting with EtOH:hexanes:Et₂NH—80:20:0.02, togive tert-butyl[(3R,5R,6S)-6-methyl-2-oxo-1-(2,2,2-trifluoroethyl)-5-(2,3,5-trifiuorophenyepiperidin-3-yl]carbamateas the first major peak, and tert-butyl[(3S,5S,6R)-6-methyl-2-oxo-1-(2,2,2-trifluoroethyl)-5-(2,3,5-trifluorophenyl)piperidin-3-yl]carbamate,the title compound, as the second major peak. MS: m/z=463.2 (M+Na).

Step G:(3S,5S,6R)-3-Amino-6-methyl-1-(2,2,2-trifluoroethyl)-5-(2,3,5-trifluorophenyl)piperidin-2-onehydrochloride

A solution of tert-butyl[(3S,5S,6R)-6-methyl-2-oxo-1-(2,2,2-trifluoroethyl)-5-(2,3,5-trifluorophenyl)piperidin-3-yl]carbamate(402 mg, 0.913 mmol) in EtOAc (10 mL) was saturated with HCl (g) andaged for 30 min. The resulting mixture was concentrated in vacuo to givethe title compound. MS: m/z=341.0 (M+1); ¹H NMR (500 MHz, CD₃OD) δ 7.20(m, 1H), 6.94 (m, 1H), 4.78 (dq, 1H, J=15.4, 9.3 Hz), 4.26 (dd, 1H,J=12.1, 6.7 Hz), 4.08-4.00 (m, 2H), 3.73 (dq, 1H, J=15.4, 8.8 Hz), 2.57(q, 1H, J=12.5 Hz), 2.36 (ddd, 1H, J=12.5, 6.6, 2.0 Hz), 1.07 (d, 3H,J=6.6 Hz).

INTERMEDIATE 5

(3S,5S,6R)-3-Amino-6-methyl-1-(2,22-trifluoroethyl)-5-(2,3,6-trifluorophenyl)piperidin-2-onehydrochloride Step A: (5S,6R &5R,6S)-6-Methyl-1-(2,2,2-trifluoroethyl)-5-(2,3,6-trifluorophenyl)piperidin-2-one

Essentially following the procedures described in Intermediate 5, butusing 2,3,6-trifluorophenylboronic acid in place of2,3,5-trifluorophenylboronic acid, the title compound was obtained. MS:m/z=326.0 (M+1).

Step B: (3S,5S,6R &3R,5R,6S)-3-Azido-6-methyl-1-(2,2,2-trifluoroethyl)-5-(2,3,6-trifluorophenyl)piperidin-2-one

To a stirred solution of lithium bis(trimethylsilyl)amide (1.0 M in THF,4.80 mL, 4.80 mmol) in THF (20 mL) at −78° C. was added a cold (−78° C.)solution of (5S,6R &5R,6S)-6-methyl-1-(2,2,2-trifluoroethyl)-5-(2,3,6-trifluorophenyl)piperidin-2-one(1.30 g, 4.00 mmol) in THF (10 mL) dropwise, keeping the internaltemperature of the reaction mixture below −65° C. The resulting mixturewas stirred at −78° C. for 30 min, then a cold (−78° C.) solution of2,4,6-triisopropylbenzenesulfonyl azide (Harmon et al. (1973) J. Org.Chem. 38, 11-16) (1.61 g, 5.20 mmol) in THF (10 mL) was added dropwise,keeping the internal temperature of the reaction mixture below −65° C.The reaction mixture was stirred at −78° C. for 30 min, then AcOH (1.05mL, 18.4 mmol) was added. The resulting mixture was allowed to warmslowly to ambient temperature and was poured into saturated aqueoussodium bicarbonate (50 mL) and the mixture was extracted with EtOAc(2×75 mL). The combined organic layers were washed with brine, thendried over sodium sulfate, filtered, and concentrated to dryness invacuo. The crude product was purified by silica gel chromatography,eluting with a gradient of hexanes:EtOAc—100:0 to 20:80, to give thediastereomeric azide products (3R,5S,6R &3S,5R,6S)-3-azido-6-methyl-1-(2,2,2-trifluoroethyl)-5-(2,3,5-trifluorophenyl)piperidin-2-one,which eluted second, and the title compound, which eluted first. MS:m/z=367.1 (M+1).

Step C:tert-Butyl[(3S,5S,6R)-6-methyl-2-oxo-1-(2,2,2-trifluoroethyl)-5-(2,3,6-trifluorophenyl)piperidin-3-yl]carbamate

To a solution of (3S,5S,6R &3R,5R,6S)-3-azido-6-methyl-1-(2,2,2-trifluoroethyl)-5-(2,3,5-trifluorophenyl)piperidin-2-one(280 mg, 0.764 mmol) and di-tert-butyl dicarbonate (217 mg, 0.994 mmol)in EtOH (5 mL) was added 10% palladium on carbon (25 mg, 0.024 mmol) andthe resulting mixture was stirred vigorously under an atmosphere ofhydrogen (ca. 1 atm) for 1 h. The reaction mixture was filtered througha pad of Celite®, washing with EtOH, and the filtrate was concentratedin vacuo to give a crude solid. The crude product was purified by silicagel chromatography, eluting with a gradient of hexanes:EtOAc 100:0 to30:70, to give the racemic title compound. Separation of the enantiomerswas achieved by SFC on a ChiralPak® IC column, eluting withCO₂:MeOH:CH₃CN—90:6.6:3.3, to give tert-butyl[(3R,5R,6S)-6-methyl-2-oxo-1-(2,2,2-trifluoroethyl)-5-(2,3,6-trifluorophenyl)piperidin-3-yl]carbamateas the first major peak, and tert-butyl[(3S,5S,6R)-6-methyl-2-oxo-1-(2,2,2-trifluoroethyl)-5-(2,3,6-trifluorophenyl)piperidin-3-yl]carbamate,the title compound, as the second major peak. MS: m/z=463.2 (M+Na).

Step D:(3S,5S,6R)-3-Amino-6-methyl-1-(2,2,2-trifluoroethyl)-5-(2,3,6-trifluorophenyl)piperidin-2-onehydrochloride

A solution of tert-butyl[(3S,5S,6R)-6-methyl-2-oxo-1-(2,2,2-trifluoroethyl)-5-(2,3,6-trifluorophenyl)piperidin-3-yl]carbamate(122 mg, 0.277 mmol) in EtOAc (10 mL) was saturated with HCl (g) andaged for 30 min. The resulting mixture was concentrated in vacuo to givethe title compound. MS: m/z=341.1 (M+1); ¹H NMR (500 MHz, CD₃OD) δ 7.33(qd, 1H, J=9.3, 4.9 Hz), 7.05 (tdd, 1H, J=9.8, 3.7, 2.2 Hz), 4.78 (dq,1H, J=15.4, 9.3 Hz), 4.22 (dd, 1H, J=12.2, 6.6 Hz), 4.06 (ddd, 1H,J=13.3, 4.5, 2.7 Hz), 3.97 (m, 1H), 3.73 (dq, 1H, J=15.4, 8.8 Hz), 2.91(qt, 1H, J=12.7, 3.1 Hz), 2.36 (ddd, 1H, J=12.7, 6.4, 2.0 Hz), 1.22 (d,3H, J=6.6 Hz).

INTERMEDIATE 6

(3S,5S,6R)-3-Amino-6-methyl-5-(2-methylphenyl)-1-(2,2,2-trifluoroethyl)piperidin-2-oneStep A: MethylN-(tert-butoxycarbonyl)-4-(2-methylphenyl)-5-oxonorleucinate

To a solution of methyl N-(tert-butoxycarbonyl)-3-iodo-D-alaninate (1.58g, 4.80 mmol) in DMF (24 mL) was added cesium carbonate (1.56 g, 4.80mmol) and the mixture was stirred at 23° C. for 45 min.1-(2-Methylphenyl)-propan-2-one (0.783 g, 5.28 mmol) and cesiumcarbonate (2.35 g, 7.20 mmol) were added and the resulting mixture wasstirred for 18 h. The mixture was filtered and water was added to thefiltrate. The mixture was extracted with ethyl acetate (3×). Thecombined organic extracts were washed with water (3×), brine, dried oversodium sulfate, filtered and concentrated. Purification by silica gelchromatography (5% ethyl acetate 40% ethyl acetate/hexane) gave thetitle compound. MS: m/z=350.1 (M+1).

Step B:tert-Butyl[(3S,5S,6R)-6-methyl-5-(2-methylphenyl)-2-oxo-1-(2,2,2-trifluoroethyl)piperidin-3-yl]carbamate

To a solution of methylN-(tert-butoxycarbonyl)-4-(2-methylphenyl)-5-oxonorleucinate (1.60 g,4.58 mmol) in dichloroethane (23 mL) were added glacial acetic acid(0.524 mL, 9.16 mmol), 2,2,2-trifluoroethylamine (1.83 mL, 22.9 mmol)and 4 {acute over (Å)} molecular sieves (500 mg). The mixture wasstirred at 23° C. for 20 min and then sodium triacetoxyborohydride (4.85g, 22.89 mmol) was added. The mixture was stirred at 23° C. for 18 h.The mixture was diluted with water and extracted with ethyl acetate(3×). Molecular sieves were removed by filtration and the combinedorganic extracts were washed with water, brine, dried over sodiumsulfate, filtered and concentrated. A solution of the residue in ethanol(45 mL) was stirred in the presence of solid potassium carbonate (1.86g, 13.49 mmol) at 60° C. for 2 h. The bulk of the ethanol was removedunder reduced pressure and the remaining slurry was then partitionedbetween water (25 mL) and ethyl acetate (150 mL). The organic layer waswashed with brine, dried over sodium sulfate and concentrated.Purification by silica gel chromatography (5% ethyl acetate→50% ethylacetate/hexane) was followed by separation of the enantiomers usingnormal-phase HPLC using a ChiralPak® AD column, eluting with 20% hexanein ethanol (0.1% diethylamine used as a modifier) to afford the titlecompound as the second enantiomer to elute. MS: m/z=423.2 (M+Na).

Step C:(3S,5S,6R)-3-Amino-6-methyl-5-(2-methylphenyl)-1-(2,2,2-trifluoroethyl)piperidin-2-one

A solution of tert-butyl[(3S,5S,6R)-6-methyl-5-(2-methylphenyl)-2-oxo-1-(2,2,2-trifluoroethyl)piperidin-3-yl]carbamate(152 mg, 0.37 mmol) in ethyl acetate (10 mL), pre-cooled to 0° C. wassparged with HCl gas for ˜1 min. The reaction mixture was allowed to sitfor 30 min at 0° C. The mixture was then concentrated to dryness toafford the title compound as a hydrochloride salt. MS: m/z=301.3 (M+1).

The intermediates appearing in the following tables were prepared byanalogy to the above intermediates, as described or prepared as a resultof similar transformations with modifications known to those skilled inthe art. The requisite starting materials were described herein,commercially available, known in the literature, or readily synthesizedby one skilled in the art. Straightforward protecting group strategieswere applied in some routes. In some cases, relevant experimentalprocedures are indicated in the tables.

TABLE 1

Relevant Intermediate R² Ar MS (M + 1) procedures 10 H3,5-difluorophenyl 309.0 Int. 3 11 H 2,5-difluorophenyl 309.0 Int. 3 12H 2,3,5-trifluorophenyl 327.0 Int. 3 13 H 2-chloro-6-fluorophenyl 324.9Int. 3 14 H 2,6-dichlorophenyl 341.0 Int. 3 15 H 2,3,6-trifluorophenyl326.9 Int, 3 16 Me 2,3,5,6-tetrafluorophenyl 359.0 Int. 4 17 Me3-fluoro-2-methylphenyl 319.1 Int. 4 18 Me 3-methylphenyl 301.2 Int. 6

INTERMEDIATE 19

(6R)-3′-Methyl-2′,5′-dioxo-5,7-dihydrospiro[cyclopenta[b]pyridine-6,4′-imidazolidine]-3-carboxylicacid Step A: Methyl(6R)-1′-(4-methoxybenzyl)-3′-methyl-2′,5′-dioxo-5,7-dihydrospiro[cyclopenta[b]pyridine-6,4′-imidazolidine]-3-carboxylate

The enantiomers of methyl1′-(4-methoxybenzyl)-3′-methyl-2′,5′-dioxo-5,7-dihydrospiro[cyclopenta[b]pyridine-6,4′-imidazolidine]-3-carboxylate(described in Intermediate 1) were separated by SFC using a ChiralPak ICcolumn, eluting with CO₂:EtOH:CH₃CN—60:20:20, to give methyl(6S)-1′-(4-methoxybenzyl)-3′-methyl-2′,5′-dioxo-5,7-dihydrospiro[cyclopenta[b]pyridine-6,4′-imidazolidine]-3-carboxylate,which was the second major peak to elute, and the title compound, whichwas the first major peak to elute.

Step B: Methyl(6R)-3′-methyl-2′,5′-dioxo-5,7-dihydrospiro[cyclopenta[b]pyridine-6,4′-imidazolidine]-3-carboxylate

To a stirred solution of methyl(6R)-1′-(4-methoxybenzyl)-3′-methyl-2′,5′-dioxo-5,7-dihydrospiro[cyclopenta[b]pyridine-6,4′-imidazolidine]-3-carboxylate(10.0 g, 25.3 mmol) in MeOH (100 mL) at ambient temperature was addedeerie ammonium nitrate (27.7 g, 50.6 mmol) and the reaction mixture wasstirred at ambient temperature for 18 h. The resulting mixture waspartitioned between H₂O (500 mL) and EtOAc (1 L) and the organic layerwas discarded. The aqueous layer was adjusted to pH=7-8 by addition of 1N aqueous NaOH and extracted further with EtOAc (2×500 mL) and thecombined organic extracts were dried over sodium sulfate, filtered, andconcentrated in vacuo. The crude solid was purified by silica gelchromatography, eluting with a gradient of CH₂Cl₂:MeOH—100:0 to 90:10,to give the title compound. MS: m/z=276.1 (M+1).

Step C:(6R)-3′-Methyl-2′,5′-dioxo-5,7-dihydrospiro[cyclopenta[b]pyridine-6,4′-imidazolidine]-3-carboxylicacid

To a solution of methyl(6R)-3′-methyl-2′,5′-dioxo-5,7-dihydrospiro[cyclopenta[b]pyridine-6,4′-imidazolidine]-3-carboxylate(450 mg, 1.64 mmol) in THF (8 mL) and H₂O (2 mL) was added 1 N aqueouslithium hydroxide (1.96 mL, 1.96 mmol). The reaction was stirred atambient temperature for 2 h, adjusted to pH≈4 by addition of 1 Nhydrochloric acid, and concentrated in vacuo to provide the titlecompound. MS: m/z=262.1 (M+1). ¹H NMR (500 MHz, CD₃OD) δ 8.96 (s, 1H),8.24 (s, 1H), 3.54 (d, 1H, J=18.1 Hz), 3.52 (d, 1H, J=17.3 Hz), 3.40 (d,1H, J=17.3 Hz), 3.39 (d, 1H, J=18.1 Hz), 2.71 (s, 3H).

EXAMPLE 1

(6R)-3′-Methyl-N-[(3S,5S,6R)-6-methyl-2-oxo-1-(2,2,2-trifluoroethyl)-5-(2,3,6-trifluorophenyl)piperidin-3-yl]-2′,5′-dioxo-5,7-dihydrospiro[cyclopenta[b]pyridine-6,4′-imidazolidine]-3-carboxamide

To a stirred mixture of3′-methyl-2′,5′-dioxo-5,7-dihydrospiro[cyclopenta[b]pyridine-6,4′-imidazolidine]-3-carboxylicacid (described in Intermediate 1, 20 mg, 0.077 mmol),(3S,5S,6R)-3-amino-6-methyl-1-(2,2,2-trifluoroethyl)-5-(2,3,6-trifluorophenyl)piperidin-2-onehydrochloride (described in Intermediate 5, 22 mg, 0.058 mmol), HOBT (12mg, 0.078 mmol), and EDC (15 mg, 0.078 mmol) in DMF (0.5 mL) was addedN,N-diisopropylethylamine (0.031 mL, 0.175 mmol), and the resultingmixture was stirred at ambient temperature for 18 h. The reactionmixture was poured into saturated aqueous sodium bicarbonate (5 mL) andextracted with EtOAc (2×10 mL). The combined organic layers were washedwith brine, dried over sodium sulfate, and concentrated in vacuo. Theresidue was purified by silica gel chromatography, eluting with agradient of CH₂Cl₂:MeOH:NH₄OH 100:0:0 to 90:10:1, to give the desiredproduct as a mixture of isomers. Separation of the stereoisomers wasachieved by SFC using a ChiralPak IC column, eluting withCO₂:MeOH:Et₂NH—75:25:0.1, to give(6S)-3′-methyl-N-[(3S,5S,6R)-6-methyl-2-oxo-1-(2,2,2-trifluoroethyl)-5-(2,3,6-trifluorophenyl)piperidin-3-yl]-2′,5′-dioxo-5,7-dihydrospiro[cyclopenta[b]pyridine-6,4′-imidazolidine]-3-carboxamide,which was the first major peak to elute, and the title compound, whichwas the second major peak to elute. HRMS: m/z=584.1715 (M+1), calculatedm/z=584.1727 for C₂₆H₂₄F₆N₅O₄. ¹H NMR (500 MHz, CD₃OD) δ 8.87 (s, 1H),8.14 (s, 1H), 7.28 (qd, 1H, J=9.0, 4.6 Hz), 7.02 (m, 1H), 4.79 (m, 1H),4.54 (dd, 1H, J=11.7, 6.8 Hz), 4.02 (m, 1H), 3.93 (m, 1H), 3.68 (dq, 1H,J=15.4, 8.8 Hz), 3.55 (d, 1H, J=18.1 Hz), 3.54 (d, 1H, J=17.6 Hz), 3.40(d, 2H, J=17.8 Hz), 3.20 (m, 1H), 2.72 (s, 3H), 2.34 (m, 1H), 1.33 (d,3H, J=6.4 Hz).

EXAMPLE 2

(6R)-3′-Methyl-N-[(3S,5S,6R)-6-methyl-2-oxo-1-(2,2,2-trifluoroethyl)-5-(2,3,5,6-tetrafluorophenyl)piperidin-3-yl]-2′,5′-dioxo-5,7-dihydrospiro[cyclopenta[b]pyridine-6,4′-imidazolidine]-3-carboxamide

To a stirred mixture of(6R)-3′-methyl-2′,5′-dioxo-5,7-dihydrospiro[cyclopenta[b]pyridine-6,4′-imidazolidine]-3-carboxylicacid (described in Intermediate 19, 36 mg, 0.139 mmol),(3S,5S,6R)-3-amino-6-methyl-1-(2,2,2-trifluoroethyl)-5-(2,3,5,6-tetrafluorophenyl)piperidin-2-onehydrochloride (described in Intermediate 16, 50 mg, 0.127 mmol), HOBT(25 mg, 0.165 mmol), and EDC (32 mg, 0.165 mmol) in DMF (1.5 mL) wasadded N,N-diisopropylethylamine (0.066 mL, 0.380 mmol), and theresulting mixture was stirred at ambient temperature for 6 h. Thereaction mixture was poured into saturated aqueous sodium bicarbonate (5mL) and extracted with EtOAc (2×10 mL). The combined organic layers werewashed with brine, dried over sodium sulfate, and concentrated in vacuo.The residue was purified by silica gel chromatography, eluting with agradient of CH₂Cl₂:MeOH:NH₄OH—100:0:0 to 90:10:1, to give the titlecompound. HRMS: m/z=602.1632 (M+1), calculated m/z=602.1633 forC₂₆H₂₃F₇N₅O₄. ¹H NMR (500 MHz, CDCl₃) δ 8.88 (s, 1H), 8.38 (br s, 1H),8.03 (s, 1H), 7.55 (d, 1H, J=4.9 Hz), 7.08 (m, 4.90 (m, 1H), 4.50 (m,1H), 4.04-3.95 (m, 2H), 3.70 (d, 1H, J=18.3 Hz), 3.61 (d, 1H, J=17.3Hz), 3.35 (m, 1H), 3.30 (d, 1H, J=18.1 Hz), 3.20 (d, 1H, J=17.6 Hz),2.89-2.77 (m, 2H), 2.68 (s, 3H), 1.30 (d, 3H, J=6.4 Hz).

The examples appearing in the following table were prepared by analogyto the above examples, as described or prepared as a result of similartransformations with modifications known to those skilled in the art.The requisite starting materials were described herein, commerciallyavailable, known in the literature, or readily synthesized by oneskilled in the art. Straightforward protecting group strategies wereapplied in some routes.

TABLE 2

Calculated Example Ar HRMS (M + 1) m/z (M + 1) 3 2,3,5-trifluorophenyl584.1717 584.1727

What is claimed is:
 1. A compound of Formula I:

or a pharmaceutically acceptable salt thereof, wherein: R¹ is selectedfrom the group consisting of: C₁₋₄alkyl, cyclopropylmethyl,cyclobutylmethyl and [1-(trifluoromethyl)cyclopropyl]methyl, each ofwhich is optionally substituted with one to four substituents as allowedby valence independently selected from the group consisting of: F andhydroxy; R² is hydrogen or methyl; when R² is hydrogen then R³ isselected from hydrogen, F or Cl; R⁴ is selected from hydrogen, F or Cl;R⁵ is hydrogen; R⁶ is selected from hydrogen or F; and R⁷ is selectedfrom hydrogen, F or Cl; except that at least two of R³, R⁴, R⁶ and R⁷must be F or Cl unless R³ is F in which case R⁴, R⁶ and R⁷ may all behydrogen; and if R⁴ is Cl then R⁷ cannot be Cl; when R² is methyl thenR³ is selected from hydrogen, methyl, F, Cl, or Br; R⁴ is selected fromhydrogen, methyl, F or Cl; R⁵ is selected from hydrogen or F; R⁶ isselected from hydrogen or F; and R⁷ is selected from hydrogen, methyl, For Cl; except that if R⁵ is F then at least three of R³, R⁴, R⁶ and R⁷must be F; and if R⁴ is methyl or Cl then R⁷ cannot be methyl or Cl; andR⁸ is selected from the group consisting of: hydrogen, C₁₋₄alkyl,cyclopropylmethyl, and cyclobutylmethyl, each of which is optionallysubstituted with one to three fluoro substituents as allowed by valence.2. The compound of claim 1, or a pharmaceutically acceptable saltthereof, wherein R¹ is C₁₋₄alkyl, optionally substituted with one tofour substituents as allowed by valence independently selected from thegroup consisting of F and hydroxy.
 3. The compound of claim 2, or apharmaceutically acceptable salt thereof, wherein R¹ is selected from:isopropyl, 2,2,2-trifluoroethyl and 2-methylpropyl.
 4. The compound ofclaim 3, or a pharmaceutically acceptable salt thereof, wherein R¹ is2,2,2-trifluoroethyl.
 5. The compound of claim 1, or a pharmaceuticallyacceptable salt thereof, wherein R² is hydrogen.
 6. The compound ofclaim 5, or a pharmaceutically acceptable salt thereof, wherein at leasttwo of R³, R⁴, R⁶ and R⁷ are F or Cl, except that if R⁴ is Cl then R⁷cannot be Cl.
 7. The compound of claim 5, or a pharmaceuticallyacceptable salt thereof, wherein R³ is F and R⁴, R⁶ and R⁷ are hydrogen.8. The compound of claim 1, or a pharmaceutically acceptable saltthereof, wherein R² is methyl.
 9. The compound of claim 8, or apharmaceutically acceptable salt thereof, wherein R⁵ is F and at leastthree of R³, R⁴, R⁶ and R⁷ are F.
 10. The compound of claim 8, or apharmaceutically acceptable salt thereof, wherein R⁵ is hydrogen and ifR⁴ is methyl or Cl then R⁷ cannot be methyl or Cl.
 11. The compoundaccording to claim 8, or a pharmaceutically acceptable salt thereof,wherein R³ is selected from hydrogen, methyl or F; R⁴ is selected fromhydrogen, methyl or F; R⁵ is hydrogen; R⁶ is selected from hydrogen orF; and R⁷ is selected from hydrogen, methyl or F; except that if R⁴ ismethyl then R⁷ cannot be methyl.
 12. The compound according to claim 11,or a pharmaceutically acceptable salt thereof, wherein R³ is hydrogen orF, R⁴ is hydrogen or F, R⁶ is hydrogen or F and R⁷ is hydrogen or F. 13.The compound of claim 1, or a pharmaceutically acceptable salt thereof,wherein R⁸ is C₁₋₄alkyl.
 14. The compound of claim 13, or apharmaceutically acceptable salt thereof, wherein R⁸ is methyl.
 15. Thecompound of claim 1, which is selected from the following:

R² Ar Me 2,3,5-trifluorophenyl Me 2,3,6-trifluorophenyl Me2,3,5,6-tetrafluorophenyl

or a pharmaceutically acceptable salt thereof.
 16. A pharmaceuticalcomposition which comprises an inert carrier and the compound of claim1, or a pharmaceutically acceptable salt thereof.
 17. A method oftreating headache in a mammalian patient in need of such treatment,which comprises administering to the patient a therapeutically effectiveamount of the compound of claim 1, or a pharmaceutically acceptable saltthereof.
 18. The method of claim 17, wherein the headache is migraineheadache.